JPH06267175A - Storage device and method for controlling the same - Google Patents

Abstract

(57) [Abstract] [Purpose] The objective is to reduce power consumption without reducing the throughput of a disk device. A hit ratio holding unit 200 that holds the current hit ratio of the cache 300, and a specified value holding unit 210 that holds the reference value of the hit ratio are provided. The disk device has a plurality of operation modes. The controller 120 compares the current hit rate with the reference value. As a result, if the current hit rate exceeds the reference value, a command is issued to move to an operation mode with low power consumption.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage device which suppresses power consumption and improves processing speed, and a control method thereof.

[0002]

2. Description of the Related Art A conventional disk device, particularly a magnetic disk device of 2.5 inches or less, is provided with a plurality of operation modes.
It is designed to reduce power consumption by selecting an operation mode. FIG. 17 shows a transition block diagram of the operation modes. The operation modes are roughly divided into the following five. The first is the read / write mode (100
0). In this mode, data is being read from the recording medium or data is being written to the recording medium. Second, seek mode (1010)
Is. This is a mode in which the read / write head is moved to the target position. Third, idle mode (102
0). This is a state in which the recording medium is in steady rotation and waiting for a command from the host system. Fourth is the standby mode (1030). In this mode, the rotation of the recording medium is stopped, and when a command is issued from the host system, the recording medium is rotated and then the command from the host is executed. Fifth, sleep mode (1040)
Is. In this mode, all functions are stopped and restarted by an initialization signal from the host system.

When the disk device is powered on, the spindle motor is activated, and in the idle mode, it waits for a command from the host system. When a data read / write command is received from the host system in this state, the mode changes to the read / write mode. Also, when a seek command arrives, the mode changes to the seek mode.

There are two cases at the timing of transition from the idle mode to the standby mode. The first timing is a method of switching the mode immediately when a command from the host system arrives. The second timing is a method of transitioning from the idle mode to the standby mode when no command comes to the disk device for a prescribed time from the host system. For example, if you set the transition time to 60 seconds, when the idle mode continues for 60 seconds,
The disk device automatically shifts to the standby mode.

Related to this type of device, for example, Nikkei Electronics, October 29, 1990.
Sun, No. 512, page 175 and JP-A-4-7685.
7 etc. are mentioned.

[0006]

The above-mentioned prior art has not sufficiently considered the data read and write processing times. For example, when the standby mode is used, the spindle motor stops, so that there is a problem that the system throughput (reading and writing speed of recorded data) is significantly reduced in the low power consumption mode.

Further, if the standby mode is always used, there is a problem that the number of times the spindle motor is started increases and the mechanical system life is shortened.

A first object of the present invention is to provide a disk device and a power control method thereof in which the system throughput is less deteriorated even when the low power consumption mode is used.

A second object is to provide a disk device which can reduce power consumption after the power is turned on.

A third object is to provide a disk device having a long life by reducing the number of times of starting the spindle motor.

[0011]

The present invention has been made to achieve the above object, and in one aspect thereof, has a plurality of operation modes and has a main storage medium and a cache storage medium as storage media. In a storage device using and, in the main storage medium, an input / output unit that receives an instruction from another device and exchanges data with another device that is necessary when the instruction is executed. Main memory reading means for reading the stored data, a function for storing the data read by the main memory reading means in the cache storage medium, and a function for reading the data stored in the cache storage medium And a cache management unit including an access count holding unit that counts the number of times a read command is received from another device and holds the count as an access count, and a read count from another device. De that is the issue the subject of instruction -
Determination means for determining whether or not the data is stored in the cache storage medium, and the determination result by the determination means,
The hit rate is calculated by using the hit number holding means for counting the number of times the data to be read is held in the cache storage medium and holding it as the hit number, and the hit number and the access number. A hit rate calculating means, and a prescribed value holding means for holding a preset first prescribed value, which serves as a reference for changing the operation mode,
The latest hit rate calculated by the hit rate calculation means is compared with the first prescribed value, and the operation mode is calculated according to the result of the comparison.
And an operation mode control means for controlling the mode, wherein the operation mode control means, as the operation mode, at least accesses the main storage medium and accesses the cache storage medium. The first mode that can access and
And less power consumption than the first mode, and
At least two second modes capable of accessing the cache storage medium are provided, and as a result of the comparison, if the hit rate is smaller than the first specified value, the operation of the storage device. The mode is shifted to the first mode, and conversely, when the hit rate is larger than the first prescribed value, the operation mode of the storage device is shifted to the second mode. What is provided is a storage device.

In this case, the slope of the hit rate change at the present time is calculated by using the hit rate holding means for storing the hit rate in at least a certain past range from the present time and the value of the hit rate stored in the hit rate holding means. And a predetermined value holding means further has a second predetermined value set in advance, and the operation mode control means has the hit rate change calculated by the tilt calculating means. Further has a function of comparing the slope of the above with the second prescribed value, and even when the hit rate is larger than the first prescribed value, when the inclination is smaller than the second prescribed value, The operation mode may not be shifted to the first mode.

As a second aspect of the present invention, in a storage device having a plurality of operation modes and using a main storage medium and a cache storage medium as storage media, while accepting a command from another device, An input / output means for exchanging data with another device which is necessary when the instruction is executed, a main memory reading means for reading the data stored in the main storage medium, and the main memory A cache management unit having a function of storing the data read by the reading unit in the cache storage medium, a function of reading the data stored in the cache storage medium, and a read command from another device. The access count holding means for counting the number of times of access and holding it as the access count, and the data that is the target of the read command from another device are As a result of the judgment by the judging means for judging whether or not the data is stored, and the result of the judgment by the judging means, the number of times that the data to be read is held in the cache storage medium is counted and held as the number of hits. Hit count holding means, hit ratio calculation means for calculating the hit ratio using the hit count and the access count, and the time from the last access from another device until the operation mode is changed. (Hereinafter "mode transition time"
Mode) and the hit rate, a mode transition time holding means for storing a predefined correspondence relationship, a specified value holding means for holding the current mode transition time, and a final access from another device. From the timing means for measuring the elapsed time from the time of receiving, the hit rate at the present time, and the correspondence relationship between the hit rate held in the mode transition time holding means and the mode transition time, -The transition time is calculated and stored in the specified value holding means, and
The operation mode control means compares the current mode transition time with the elapsed time and controls the operation mode according to the result of the comparison. , A first mode capable of performing at least access to the main storage medium and access to the cache storage medium, power consumption lower than that of the first mode, and at least the above At least two operation modes, that is, a second mode capable of accessing the cache storage medium, are provided, and as a result of the comparison, if the elapsed time exceeds the mode transition time, The operation mode of the storage device is to be transferred to the second mode,
A storage device is provided.

In this case, using the hit rate holding means for storing the hit rate within a certain range from the present time to the past, and the value of the hit rate stored in the hit rate holding means, the inclination for obtaining the inclination of the hit rate change at the present time Calculation means,
And the predefined correspondence relationship between the mode transition time held by the mode transition time holding means and the hit rate is defined including the correspondence relationship with the slope of the hit rate change. The operation mode control means is
The processing for obtaining the mode transition time is performed by using the hit rate and the slope of the hit rate at the present time, the mode transition time held by the mode transition time holding means, the hit rate, and the slope of the change in the hit rate. It is also possible to use the correspondence relationship of

In the first and second aspects of the present invention, when the power is turned off, at least the data stored in the cache storage medium and the access count holding means are held. It is preferable to provide data protection means for storing and protecting the access count and the hit count held in the hit count holding means.

According to a third aspect of the present invention, a storage device using a disk type main storage medium and a cache storage medium as a storage medium accepts an instruction from another device and executes the instruction. I / O means for transmitting and receiving data to and from other devices, which is necessary in connection with the main memory, main memory reading means for reading the data of the main memory medium, and data read by the main memory reading means. Is stored in the cache storage medium, and a cache management means having a function of reading data stored in the cache storage medium;
When a data read command is received from another device when the data is not in a rotation state in which the data can be read, it is determined whether the data is stored in the cache storage medium,
When stored, a storage device comprising: a control unit that reads out and outputs the data stored in the cache storage medium without activating the hand storage medium. Provided.

According to a fourth aspect of the present invention, in a storage device that uses a disk-type main storage medium and a write cache storage medium as the storage medium, while accepting an instruction from another device, Input / output means for transmitting / receiving data to / from other devices necessary for execution, main memory writing means for writing data in the main storage medium, and data writing in the main storage medium When a data write command is received from another device when the data is not in a rotation state that allows the data to be stored, the data is stored in the write cache storage medium and the data is written to the write cache storage medium. At that point, the fact that the write command has been executed is notified to the other device, and thereafter, the write instruction is written to the write cache storage medium at a preset timing.該De - storage device is provided, characterized in that and a control means for writing to the hand storage medium data.

[0018]

In the first and second modes, the operation mode of the storage device is controlled by using the hit rate and the slope of the hit rate calculated by the hit rate calculating means.
Since the function of a specific part of the storage device (for example, a spindle motor or the like when a disk type is used as the main storage medium) is stopped, deterioration of system throughput can be prevented.

Even if the disk type main storage medium cannot immediately read the data, the data can be read from the disk device with a probability corresponding to the current cache hit rate. Therefore, deterioration of system throughput can be prevented.

When the power is turned on again, the data recorded and retained when the power was last turned off, and the number of accesses up to the last time,
The number of hits can be recovered respectively, the hit rate up to the previous time and the data in the cache can be used, and the power consumption can be reduced even after the power is turned on.

In the third and fourth modes, when the main storage medium is not in the rotation state in which data can be written (that is, when the spindle motor is stopped, etc.), the write data is written in the write cache storage medium. Hold. Then, after that, at a preset timing, for example, when the main storage medium is rotated, the data written in the write cache storage medium is collectively written in the main storage medium. As a result, the number of times the main storage medium, that is, the spindle motor or the like, is activated can be reduced.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

First, an outline of the magnetic disk device of this embodiment will be described with reference to FIG. A mechanism unit (HDA) 500 of the magnetic disk device records a magnetic recording disk 510 for recording and holding data, a spindle motor 520 for rotating the magnetic recording disk 510, and a magnetic recording disk 510 for recording or recording data. A magnetic head 530 for reading data from the plate 510 and a magnetic recording disk 5 for the magnetic head 530.
Actuator 540 for moving to any position on 10
And are included.

The spindle motor 520 is controlled by the spindle motor control circuit 150, and the rotation speed is kept constant. The controller 120 also controls the rotation / rotation of the spindle motor 520 through the power supply controller 400.
The stop can be controlled. Actuator 540
Are controlled by the positioning control circuit 140. This allows the magnetic head 530 to move to any position on the magnetic recording disk 510.

A read operation in which the host reads data from the disk will be described with reference to FIG. When a read command is received from the host, the controller 120 first determines whether or not the data desired by the host exists in the cache 300. If the desired data is in the cache 300, a cache read hit occurs and the data in the cache 300 is transferred to the host. Conversely, if the desired data is not in the cache 300, a cache read miss occurs, the desired data is read from the magnetic recording disk 510, and the host is accessed through the R / W circuit 130, the hard disk controller (HDC) 110, and the interface controller 100. Will be transferred to. At this time, the data is transferred to the host, and at the same time, the data is recorded in the cache 300. This allows
After that, when a read command for the data comes, a cache read hit occurs. At this time, the cache hit rate R during read is (hit rate R) = {(cache read hit count)
/ (Read count)} × 100. The cache read hit can significantly reduce the data read time.

Next, a write operation in which the host writes data to the disk will be described with reference to FIG. The data to be recorded is the interface controller 100, the hard disk controller (HDC) 110, the R / W circuit 130.
Through the magnetic head 530 to record on the magnetic recording disk 510. At this time, the record data is also recorded in the cache 300 at the same time.

The disk device of this embodiment is provided with a plurality of operation modes, and the timing of the operation mode transition is determined by using the hit rate of the cache 300 or the like, so that the deterioration of the system throughput is minimized. The feature is that the power consumption is reduced while being suppressed. Therefore, in the following, this point will be mainly described.

R / W circuit 130, positioning control circuit 14
0, spindle motor control circuit 150, spindle motor
Each of the controllers 520 and the like has its own operation mode (hereinafter, the operation mode unique to each of these units is distinguished from the operation mode of the entire disk device as "unique operation". "Mode".). In addition to the normal operation mode, each has its own operation mode with low power consumption (or operation mode that stops operation and does not consume power). An operation mode with low power consumption, which is uniquely provided in each unit, is called a "specific power saving mode" to distinguish it from a low power consumption mode for the entire disk device.) The spindle motor 520 of this embodiment stops rotating in the inherent power saving mode, while rotating in the normal operation mode. Each of these units is configured to be able to transit between the specific small power mode and the normal operation mode according to a control command from a power supply controller 400 described later.

The power supply controller 400 responds to a command from the controller 120, and the spindle motor control circuit 150, the spindle motor 520, and the like have their own operation motors.
It has a function to change the mode.

The controller 120 has an operation mode definition table defining the operation mode of the entire disk device (see FIG. 2). The operation mode definition table defines how the individual operation mode for each of the above-mentioned units (for example, the spindle motor 520, etc.) in each operation mode is set. In this embodiment,
On the operation mode definition table, "normal mode" and "
Two types of operation modes, "low power consumption mode" are defined.

The "low power consumption mode" is a mode in which the spindle motor 520, the spindle motor control circuit 150, etc. are operated in an inherent power saving mode. It is not particularly limited which part is changed to the unique power saving mode. However, in the present embodiment, from the viewpoint of suppressing the power consumption, at least the spindle motor 520 is defined to be the unique power saving mode in the low power consumption mode. That is, in the low power consumption mode, the rotation of the spindle motor 520 is stopped. On the contrary, even in the low power consumption mode, at least the controller 120 itself needs to be kept in a command receivable state. In addition, the power supply controller 40
Also for 0, the control command from the controller 120 is maintained. In addition, in this embodiment, even in the low power consumption mode, the low power consumption mode is defined so that reading from the cache 300 and writing to the cache 300 are possible. In this embodiment, the low power consumption mode corresponds to the "second mode" in the claims.

The "normal mode" means the low power consumption mode.
This is a mode in which there are fewer parts that are set to the unique power saving mode than the modes. However, it is not always necessary that all parts are in the unique power saving mode. In the present embodiment, in the normal mode, at least the spindle mode is set in order to quickly perform the read operation and the like.
The motor 520 and the spindle motor control circuit 150 are not set to the unique power saving mode. That is, in the normal mode, the spindle motor 520 is rotated. The normal mode corresponds to the "first mode" in the claims.

Further, the controller 120 of this embodiment is
Each time a read command comes from the host, the hit rate holding unit 20
It has a function of updating the access count and cache hit count held at 0. Further, the hit rate is calculated using these values, and the hit rate is calculated by the hit rate holding unit 2
00 has a function of storing the data in "00". Further, the controller 120 is configured to select the operation mode described above according to the value of the hit rate. Then, it has a function of outputting a control command corresponding to the selected operation mode to the power supply controller 400 by referring to the operation mode definition table. The details of the operation mode selection will be described later.

In addition to this, the controller 120 of the present embodiment.
Is a function for storing the contents of the hit ratio holding unit 200, the specified value holding unit 210, and the cache memory 300 in the magnetic recording disk 510, a write cache is set in the cache 300, and this is used to perform a write operation. It also has a function to prevent throughput drop. Note that these functions will be described in detail later.

The hit ratio holding unit 200 is a memory for storing the number of read accesses from the host, the number of cache hits, the cache hit ratio calculated using these, the hit ratio slope ΔR, and the like. .

The specified value holding unit 210 is a memory for storing various control values necessary for controlling the operation mode. As will be described later, three methods can be considered as a method for selecting the operation mode by the controller 120, and the contents of the control value to be stored are different for each method. 1st, 3rd
There is a spindle motor stop specified value in the above method, a fixed time t for stopping the spindle motor 520, and a mode transition time t'in the second and fourth methods. It should be noted that the concrete values of these control values and the concrete contents of the functions f and g which define the mode transition time, which will be described later, are determined by any one of the throughput, the power consumption, etc. in the operation control. The value is determined depending on whether the point of is more important.

The cache 300 reads data from the magnetic recording disk 510 in order to improve throughput.
Is a semiconductor memory that holds data. Further, a write cache is set in the cache 300 and has a function of temporarily holding write data to the magnetic recording disk 510.

The non-volatile memory 310 is for storing and storing the data in the cache 300 in the event of an emergency such as a voltage drop.

The secondary power supply source 450 is used in case of a power failure or the like.
It is for supplying electric power necessary for executing the data protection operation to each unit. The power of the secondary power supply source 450 is configured to be supplied by the power supply controller 400 to at least a portion necessary for executing the protection operation.

Incidentally, in the claims,
The output means "is mainly the interface controller 1
00, realized by hard disk controller 110
It is what is done. "Main memory reading means", "Hand memory"
The "writing means" mainly refers to the R / W circuit 130, the positioning
Control circuit 140, spindle motor control circuit 150, etc.
Is realized by. ”Cache manager
The term "dan" mainly refers to the controller 120 and the hard disk.
It is realized by the controller 110. ”
Access count holding means "," hit count holding means "
The hit rate holding means "is defined by the hit rate holding unit 200.
It will be realized. "Judgment means", "Hit rate calculation
Means "," motion mode control means "," timekeeping means "," control "
The "means" is mainly realized by the controller 120.
It is what is done. "Specified value holding means" means specified value holding
It is realized by the holding unit 210. "Data protection
The protection means "mainly means the non-volatile memory 310 (or
Magnetic recording disk 510), controller 120, etc.
It will be realized. Also, hold the mode transition time.
The “step” is realized by the magnetic recording disk 510.
is there. However, each part works in close cooperation.
Therefore, the above-mentioned correspondence with the claims is strict.
Not dense.

Here, a general state of the transition of the cache hit rate, which is the premise of the operation mode control, will be described with reference to FIG. When no data is stored in the cache 300, the hit rate is naturally 0%. The hit rate gradually increases as the disk device is used for a long time (note: more accurately, as data is read repeatedly). However, when it reaches a certain level, it becomes saturated, and beyond that, the hit rate hardly increases. The capacity of the cache 300 is one factor that determines the saturation point of the hit rate. When the cache 300 has a sufficient capacity, or when specific data is repeatedly read, the hit rate may exceed 90%. On the contrary, when the capacity of the cache 300 is small (for example, about several hundreds of kilobytes), the hit rate hardly increases.

Next, the operation mode by the controller 120 will be described.
The control of the mode will be described in detail. There are several possible operation mode control methods (selection methods), but the following four methods are employed in this embodiment.

The first method will be described.

In this method, the specified value holding unit 210
The spindle motor stop regulation value set in advance is held. The reference value referred to as "spindle motor prescribed value" is used as a reference when determining the operation mode of the disk device, and whether or not the spindle motor 520 is simply stopped. It is not used only as a reference. However, from the viewpoint of suppressing low power consumption, whether or not the spindle motor 520 is rotated is important, and is therefore referred to as "spindle motor stop regulation value" here.

The controller 120 always determines whether or not the cache is hit each time a read command is received from the host.

When the cache hits, the data is read from the cache 300 and transferred. Further, the number of accesses stored in the hit rate holding unit 200 is updated, and the hit rate is calculated / updated.
Then, the hit rate calculated at this time is compared with the specified value of the spindle motor.

As a result, if the new hit rate exceeds the spindle motor stop regulation value, the state before the read operation at this time was the normal mode or the low power consumption. Regardless of whether it was in the mode or not, it will operate in the low power consumption mode thereafter. Therefore, the control command is output to the power supply controller 400 based on the definition of "low power consumption mode" in the above-mentioned operation mode definition table. The power supply controller 400 issues a command according to the instruction to change the peculiar operation mode of each unit. For example, a spindle motor 520 or a spindle motor
The controller control circuit 150 is set to the unique power saving mode (Note: in this embodiment, the spindle motor 520 is stopped in the unique power saving mode). In FIG. 3, the spindle motor stop regulation value is set to 75.00%. The hit rate increases with use, and at time P when the hit rate exceeds 75.00%, the operation mode is changed and the spindle motor 520 is stopped.

The state before the read operation is "normal mode".
If the hit rate is smaller than the spindle motor specified value even though the cache hits (that is, the hit rate has increased), it will remain in the normal mode thereafter. To be done.

On the other hand, when a cache miss occurs, the controller 120 once selects the normal mode regardless of the operation mode at that time, and the operation mode definition table. The spindle motor 52 according to the bull
0, the positioning control circuit 140 and the R / W circuit 130 are brought into a normal operation state. Then, the data is read from the magnetic recording disk 510 and transferred. It is more effective from the viewpoint of suppressing power consumption if the timing for returning the positioning control circuit 140 and the R / W circuit 130 to the normal operating state is the time when the spindle motor 520 reaches a certain rotation. After this, the controller 120 further
The number of accesses stored in the hit rate holding unit 200 is updated, and the hit rate is calculated and updated. Then, the new hit rate calculated at this time is set to the spindle mode.
Compare with the specified value.

If a cache miss occurs during the operation in the normal mode, the cache rate is naturally smaller than the specified value of the spindle motor. The motor 520 continues to rotate.

When a cache miss occurs during operation in the low power consumption mode, the hit rate after update is
It may be smaller than the specified value for the spindle motor, or may be larger than the specified value for the spindle motor. If the hit rate becomes smaller than the specified value for stopping the spindle motor, the "normal motor" will be used thereafter.
Therefore, the spindle motor 520 or the like which is started to read the data having the cache miss is allowed to continue the operation as it is. On the other hand, the hit rate is equal to or more than the specified value for stopping the spindle motor. If
It returns to the low power consumption mode again. Therefore, the spindle motor 520 and the like started to read the data having the cache miss are stopped again after the elapse of the predetermined time t. Incidentally, during the fixed time t, a cache read miss,
Alternatively, when the write operation occurs, the hit rate is confirmed again and the measurement of the constant time t is restarted from that point.

The spindle motor stop regulation value and the like stored in the regulation value holding unit 210 are set by a command from the host side connected to the disk device. For example, when the interface between the host and the hard disk is SCSI, setting is performed using a vendor unique command as shown in FIG. Note that the above-mentioned controller 120 receives this command and selects the operation mode based on the cache hit rate.

The host is the current hit rate holding unit 2.
It has a command that can read the numerical value in 00. For example, when the interface is SCSI, it has commands unique to each company as shown in FIG. 5, and the host can know the current hit rate. As a result, the user who uses the disk device according to the present invention can obtain a guide for the set value.

The operation of the controller 120 to which the first method is applied will be described in more detail and specifically with reference to the flowchart of FIG.

A read command comes from the host (step 7)
00), it is determined whether or not the cache is hit (step 702). As a result, if there is a cache read hit, the data is transferred from the cache 300 (step 710). Furthermore, the hit rate holding unit 20
The access count and hit count stored in 0 are incremented (step 712), and then the hit ratio is calculated (step 714). Then, the hit rate is compared with the spindle motor stop regulation value (step 71).
6). As a result of the comparison, if the hit rate is equal to or higher than the specified value for stopping the spindle motor, then the operating state of the spindle motor 520 is checked (step 72).
0). When the spindle motor 520 is rotating (that is, in the normal mode), the spindle motor 520 is stopped in order to shift to the low power consumption mode. Similarly, with respect to the other parts, the peculiar motion mode of each part is maintained or changed in accordance with the motion mode definition table (step 722). Then, the processing is finished as it is (step 749).

If the spindle motor is stopped in step 720 (that is, in the low power consumption mode), the processing is terminated as it is (step 7).
49). Also, in step 716, if the hit rate is smaller than the spindle motor stop regulation value,
The processing is terminated as it is (step 749).

If there is a cache read miss in step 702, the rotation of the spindle motor 520 is checked (step 730). As a result, when the spindle motor 520 is rotating (that is, in the normal mode), the R / W circuit 130 or the like reads data from the magnetic recording disk 510 and transfers the data. It is performed (step 732). After that, the access count is incremented (step 734) and the hit rate is calculated and stored (step 736). Then, the processing is terminated as it is (step 749), and the operation is continued in the normal mode even after this.

When the spindle motor 520 is stopped in step 730 (that is, the low power consumption mode is selected).
If it is in the normal mode, the spindle motor 520 is started to shift to the normal mode (step 740), and it is waited for the steady rotation (step 741). When steady rotation is reached, the magnetic recording disk 510 is read by the R / W circuit 130 and the like.
The data is read from and the data is transferred to the host (step 742). After that, the access count and the like are incremented (step 743), and the hit rate is calculated (step 744). Then, the hit rate calculated at this time is compared with the spindle motor stop regulation value (step 745). As a result of the comparison, if the hit rate is less than the specified value for stopping the spindle motor, the "normal mode" continues thereafter.
In this normal mode, the spindle motor 520 is always rotated. Therefore, the timer for counting the constant time t is invalidated ( On the other hand, when the hit rate is larger than the spindle motor stop regulation value in step 745, the timer is enabled (step 747) and the count value corresponding to the constant time t is set. (Step 748) Step 74
After 6 and 748, the process ends (step 74).
9).

However, if the timer is enabled in step 748, steps 750 through 7 are performed.
A timer interrupt, designated as 59, occurs. When a timer interrupt occurs (step 750), the controller 120 confirms the count value of the timer (step 75).
2). When the count value is 0, that is, when the constant time t set in step 748 has elapsed, the operation mode definition table is followed in order to return to the low power consumption mode again. , Spindle motor 520 is peculiar power saving mode (Note: in this embodiment, it is in a stopped state)
(Step 756). Further, the circuits of other unnecessary parts (the positioning control circuit 140, the spindle motor control circuit 150, and the R / W circuit 130) are also shifted to the unique power saving mode (step 758).

A second method of controlling the operation mode will be described.

In this method, during normal mode operation, if no command is received from the host for a time t'determined according to the hit rate at that time, the spindle motor 520 is stopped and the low power consumption mode is set. -It is to move to DO. However, even in this low power consumption mode, the cache 30
A circuit that can read from 0 and write to the cache 300 is driven. In the description of the second and fourth methods described later, the time t ′ from the last command to the disk device until the spindle motor is stopped is called “mode transition time”.

The mode transition time t'can be expressed as a function of the hit rate R as shown in the following mathematical formula 1.

[0063]

[Mathematical formula-see original document] t = f (R) The function f is the default, and is held in the magnetic recording disk 510 in advance. Then, the power supply of the disk device is turned off.
The function is read out at the time when it is set to N, and the function is held in the controller 120. Then, the controller 120 obtains the mode transition time using the function f and the hit rate, and stores it in the specified value holding unit 210.

The function f is constructed so that it can be given from the host side, and transition time control suitable for the system used can be performed. For example, the function f in FIG. 7 has a mode transition time of 300 seconds and a hit rate of 2 when the hit rate is 0%.
5 points, the mode transition time is 295 seconds, the hit rate is 50%, the mode transition time is 280 seconds, the hit rate is 75%, the mode transition time is 180 seconds, and the hit rate is 100%, the mode transition time is 0 seconds. It is an interpolation curve that passes through. When the function f is defined as shown in FIG. 7, the mode transition time becomes long when the hit rate is low, and the mode transition time becomes short when the hit rate is high. The function f can be changed by changing the mode transition time at the above five points.

The controller 12 in this second method
The operation of 0 will be described in more detail and specifically with reference to the flowchart of FIG.

A read command comes from the host (step 7)
60), the controller 120 determines whether the cache is hit (step 762). In the case of a cache read hit, the data is read from the cache 300 and transferred (step 764), and the number of hits and the like stored in the specified value holding unit 210 is incremented (step 765).

If there is a cache read miss in step 762, then the spindle motor 5
20 rotation checks are performed (step 770). When the spindle motor is rotating (that is, in the normal mode), the data is read from the magnetic recording disk 510 and the data is transferred (step 772). On the other hand, when the spindle motor 520 is stopped (that is, in the low power consumption mode), the spindle motor 520 is activated (step 780) and waits for steady rotation (step 782). Then, after the steady rotation is reached, the data is read from the magnetic recording disk 510 and transferred (step 784).

In any of steps 765, 772, and 784, after that, the number of accesses is incremented (step 766) and then the hit ratio R is calculated (step 767). Then, according to the function f (R),
The mode transition time corresponding to the current hit rate R is calculated, this is set in the timer (step 768), and the processing is ended (step 769).

After that, the timer interrupt shown in steps 790 to 798 is generated at a predetermined timing.

When a timer interrupt occurs (step 7)
90) and confirm the value of the timer (step 791). If the count value of the timer is 0 (that is, step 76
If the mode transition time set in 8 has elapsed), the spindle motor 520 is stopped (step 794). Further, circuits of unnecessary parts (positioning control circuit 140, spindle motor control circuit 150, R / W circuit 130)
Etc.) as a unique power saving mode (step 796).

A third method of controlling the operation mode will be described.

This method is based on the first method described above, and controls the operation mode of the disk device by using not only the hit rate at that time but also the hit rate before that. In the present embodiment, control is performed using the current slope ΔR of the hit rate and the current hit rate R. The hit ratio and its slope ΔR

Is the following

[Equation 2],

It is defined by

[0074]

[Equation 2] (hit rate R) = {(cache read hit count) / (read count)} × 100

[0075]

ΔR = dR / dt When the latest hit rate is stored in the hit rate holding unit 200, the ΔR = dR / dt controller 120 does not erase at least the value of the hit rate in the past certain range based on the present time. leave. Further, the slope ΔR of the change in the hit rate at the present time is calculated from the hit rate in a certain range in the past from the present time.
The past fixed range is not particularly limited as long as it is a range sufficient to calculate the inclination.

Then, the controller 120 determines the operation mode in consideration of both the current hit rate and the slope ΔR. When the slope ΔR is negative (that is, when the hit rate tends to decrease), it can be considered that cache read misses occur continuously. Therefore, in this case, even if the hit rate is equal to or higher than the spindle stop specified value, the controller 120 causes the spindle motor 520 to
The spindle motor 520 continues to rotate (that is, the normal mode is maintained) until the inclination ΔR becomes close to 0 without stopping. On the other hand, when the slope ΔR is 0 or a positive value (that is, when the hit rate tends to be maintained or rises), if the hit rate is equal to or higher than the spindle stop specified value, in principle (the above first Method), the spindle motor 520 is stopped, and the mode is changed to the low power consumption mode.

When the hit rate R at the present time is smaller than the specified value for stopping the spindle motor, the value of the inclination .DELTA.R is not taken into consideration in the operation mode control.
Normal mode.

A fourth method of controlling the operation mode will be described.

This method is based on the second method described above, and controls the operation mode of the disk device by using not only the hit rate at that time but also the hit rate before the current time. In the present embodiment, control is performed using the current slope ΔR of the hit rate and the current hit rate R. Note that the current slope of the hit rate, ΔR, etc.

The definition is as described above.

[Equation 2],

As shown in [Equation 3].

In this method, the function g of the mode transition time is
Is defined as a function of the hit rate R and the slope ΔR.
An example of the function g is shown in FIG.

As described above, when the slope ΔR is a negative slope (that is, when the hit rate tends to decrease).
Can be considered as consecutive cache read misses. Therefore, the function g is defined such that the larger the hit rate R, the shorter the mode transition time. Further, it is defined that the mode transition time becomes longer as the gradient ΔR becomes smaller (that is, the tendency of lowering the hit rate becomes stronger). Therefore, in this fourth method,
Even if the hit rate R is the same, the smaller the gradient ΔR at that time, the longer the mode transition time.

The curve showing the mode transition time (that is, the function g) may be changed steplessly or stepwise according to the value of the gradient ΔR. I don't care.

As described above, in this embodiment, since the operation mode is controlled according to the hit rate (that is, the possibility of restarting the spindle motor 520), the system throughput is deteriorated. It is possible to reduce power consumption while minimizing the above. By the way, when controlling the operation mode using such a hit ratio, the contents of the cache 300 and the value of the hit ratio disappear when the power of the disk device is turned off, so the power is turned on / off. Each time, the start rate starts from 0. This is a matter of past experience (eg
Not only can the data stored in the cache, hit rate, etc.) not be fully utilized, but the operation time in normal mode will be longer than necessary, and the effect of suppressing power consumption will be fully exerted. become unable. Therefore, in order to solve this problem, the present embodiment also has a function of keeping the contents of the cache 300, the hit rate, etc. even when the power is turned off. Below, about this function,
The processing executed by the controller 120 when the power is turned on / off will be mainly described.

When the power is turned off, the controller 120 records the data in the cache 300 in a specific area on the magnetic recording disk 510. At this time, the hit rate holding unit 2
Values such as the number of accesses of 00 and the number of hits are also held on the magnetic recording disk 510 or in the non-volatile memory 310. Then, when the power is turned on next time, the data in the previously used cache recorded in the specific area on the magnetic recording disk 510 when the power is turned off is restored to the cache 300. Further, the number of accesses and the number of hits held on the magnetic recording disk 510 or in the non-volatile memory 310 at the previous power-off time are returned to the hit rate holding unit 200.

By using such a power ON / OFF sequence, the cache hit rate can be maintained and the low power consumption mode can be fully utilized even after the power is turned on.

For example, when the capacity of the cache 300 is 4 Mbytes, a 16 Mbyte area is secured on the innermost circumference of the magnetic recording disk. When the power is turned off, the same data in the cache 300 is recorded four times in this 16 Mbyte area. The same data is recorded a plurality of times in order to improve the reliability of data.

Further, when the power is abnormally turned off (for example, power failure), there is a possibility that the data in the cache 300 cannot be recorded on the magnetic recording disk 510 or the like. Therefore, when the power is abnormally turned off, the contents of the cache 300 and the hit rate are not retained (updated). Therefore, when the power is turned on next time, the contents of the cache 300 when the power was turned off most recently and the access count and hit count at that time are restored.

Although not particularly described here, the contents stored in the specified value holding unit 210 may be held similarly when the power is turned off.

Still another function of this embodiment will be described.

In the low power consumption mode described above, the spindle motor 520 is stopped and only the data can be read from the cache 300 and written to the cache 300. Therefore, when a data write command comes during the operation in the low power consumption mode (that is, when the spindle motor is stopped), first,
The spindle motor 520 is started and the spindle motor 5
Data will be recorded when 20 reaches steady rotation. For this reason, the throughput is reduced until the spindle motor 520 is steadily rotated.

Therefore, the present embodiment has a function of preventing a decrease in throughput during a write operation. The function will be described below.

When the spindle motor 520 is stopped, the controller 120 installs a write cache having a capacity equal to or less than that of the volatile memory 310 in the cache 300. When a write command comes when the spindle motor 520 is stopped, or when the spindle motor 520 is rotating but is not in a rotation state in which writing can be performed immediately (for example, the rotation is not constant), It is assumed that the data is written in the write cache and the processing of the write instruction is completed. Thus, by temporarily holding the write data to the magnetic recording disk 510 in the write cache, the spindle motor 520 is not activated (or
The write command can be processed (without waiting for the rotation of the spindle motor 520 to reach a predetermined rotation state).

The write data temporarily stored in the write cache is stored in the magnetic recording disk 5 at the following four timings.
Recorded on 10.

The first timing is when a cache read miss occurs and the spindle motor 520 is activated. When a cache read miss occurs, the controller 120 activates the spindle motor 520 to read the data. After that, the data in the write cache is recorded on the magnetic recording disk 510 by using the interval between the commands. In other words, it is a method of writing the data in the write cache to the magnetic recording disk 510 when the spindle motor 520 is activated for some reason.

The second timing is when the write cache is full. The controller 120 is
When the write cache becomes full, the spindle motor 520 is activated to record the data in the write cache on the magnetic recording disk 510.

The third timing depends on a command from the host. Prepare a write cache flush instruction. When this command is issued from the host, the spindle motor 520 is activated and the data in the write cache is recorded on the magnetic recording disk 510.

The fourth timing is when the power is off. When turning off the power, the cache 300 is used as described above.
The data in is stored. At this time, the data in the write cache is also recorded on the magnetic recording disk 510.

As a special case other than the above, when the size of the file to be written is relatively large (for example,
The size of the file you want to write is 50 of the cache capacity.
%), The write cache is not used and the spindle motor 520 is activated at that time to directly record on the magnetic recording disk 510. At this time, the data in the write cache is also written in the magnetic recording disk 510. By doing this, cache 3
00 can be used efficiently, and the number of times of starting the spindle motor 520 can be reduced.

As described above, when the write cache is used, the capacity of the write cache is determined by the capacity of the non-volatile memory 310. This is to prepare for power shutdown in an emergency. For example, when the power is cut off due to a power failure or the like, the data in the write cache is lost. In this case, the user data disappears and the reliability of the magnetic disk device is lost. Therefore, in this embodiment, in order to deal with such a situation, the secondary power supply source 45 is supplied via the power supply controller 400.
0 is set.

In an emergency, the power supply controller 400
Power is supplied only to the minimum necessary parts such as the controller 120, the cache 300, and the non-volatile memory 310.
At this time, electric power is supplied from the secondary power supply source 450 via the power supply controller 400. In this state, the controller 120 saves the data in the write cache in the non-volatile memory 310. Therefore, the secondary power supply source 450 only needs to have a capacity capable of performing this processing.

However, the nonvolatile memory 310 is unnecessary when the power supply is reliable or when the host system is driven by a battery like a notebook computer. Therefore, the capacity of the write cache is limited to the capacity of the cache 300. Further, as long as the power capacity of the secondary power supply source 450 and the storage capacity of the non-volatile memory 310 have a margin, the entire contents of the cache 300 and the data in the hit rate holding unit 200 and the specified value holding unit 210 are stored. Also, and may be stored in the non-volatile memory 310. Further, the spindle motor 520 may be activated to directly write on the magnetic recording disk 510, and in this case, the non-volatile memory 310 becomes unnecessary.

As described above, in this embodiment, since the operation mode is controlled by using the cache hit rate or the like, the deterioration of the throughput due to the use of the low power consumption mode is minimized. You can keep it to the limit. It is also possible to prevent the throughput from being lowered during the write operation. Further, the data can be protected even in the case of a power failure. In addition to this, spindle mode
By reducing the number of restarts of the controller 520, the operating time of the mechanical system can be reduced and the life of the device can be extended.

In the above embodiment, there are two operation modes, "normal mode" and "low power consumption mode", but the number of operation modes is increased. Further, fine control may be performed. In this case, a plurality of prescribed values (for example, the spindle motor stop prescribed value described above) for defining the operation mode are provided. Further, with respect to the peculiar operation mode of each part such as the spindle motor 520, not only the "normal mode" and the "specific power saving mode" but also more kinds of peculiar operation modes are specified. If
It enables more precise power control. Furthermore, instead of changing the operation mode, the power supply itself to each part
The configuration may be N / OFF.

In the above embodiment, the main functions of the present invention such as the calculation of the hit ratio and the selection of the operation mode are the controller 1.
20 was in charge. However, the specific configuration of the present invention is not limited to this, and the above-described calculation and the like may be dispersed in each unit. Second such example
Will be described as an example.

In the second embodiment, a part of the functions of the present invention is assigned to the cache control LSI. FIG. 10 shows the overall configuration of this embodiment and the position of the cache control LSI.

The cache control LSI 600 is
It is located between the interface controller 100 and a hard disk controller (HDC) 1100. The cache 300 is managed by the cache control LSI 600. The cache control LSI 600 is controlled by the controller 1200.

The controller 1200 of this embodiment is provided with an operation mode definition table which defines the operation mode of the disk device. Then, based on the value of the hit rate or the like calculated by the hit rate calculation unit 670 or the like, a command is issued to the power control controller 400, and the operation mode of the disk device is controlled.
It has a function to control and change the mode. However, the controller 1200 of this embodiment is the same as the controller 1200 of the above embodiment.
Unlike the cache 120, it does not have a function for determining a cache hit miss, a function for calculating a hit rate, a function for storing a hit rate, and the like. In the present embodiment, these functions are performed by the hit ratio calculation unit 670, the cache control unit 660, which the cache control LSI 600 internally has.
This is performed by the prescribed value holding unit 680 and the like.

The power supply controller 400, the interface controller 100, the cache 300, the R / W circuit 130, and other parts not shown in this figure are basically the same as those in FIG. It has a function.

FIG. 11 shows the internal structure of the cache control LSI 600. Cash control LS
I is connected to the interface controller 100 by the DMA 620. Cache control LSI
Is connected to the hard disk controller (HDC) 110 by the DMA 630. DMA620 and DMA
Since 630 absorbs the difference in transfer speed,
FIFO (FirstIn First Out Me)
mary) 625, FIFO 635. The cache control unit 660 controls the cache 300 via the cache interface 610.
The cache control unit 660 has a function of executing a data replacement algorithm and a data exclusion algorithm. Further, the controller 120 has a function of performing cache hit / miss determination, which is performed by the controller 120 in the above embodiment.

The hit ratio calculation unit 670 has a function of calculating the cache hit ratio R and the slope ΔR of the hit ratio for each access from the host side, and holding the value. Furthermore, it also has a function of determining the mode transition time and the like. The function is the controller 12 in the above embodiment.
0, the hit rate holding unit 200 and the like.

The specified value holding unit 680 corresponds to the specified value holding unit 210 in the above-described embodiment.

The functions of the respective parts mentioned here are merely outlines, and the details thereof differ depending on which of the four kinds of operation mode control methods is used. Also,
Each unit may not have all of the functions listed here. For example, as the operation mode control method, the first
It goes without saying that the method of (1) does not have the function of calculating the slope ΔR of the hit rate.

[0114] The "input / output means" referred to in the claims is mainly the interface controller 10.
It is realized by 0. The “main memory reading means” and the “hand memory writing means” mainly include the R / W circuit 13.
It is realized by 0 or the like. The "cache management means" mainly refers to the cache control unit 6
It is realized by 60. "Access count holding means", "hit count holding means", "hit rate holding means", "hit rate calculation means", "determination means", "operation mode"
The "control means" and the "timer means" and the "control means" are realized by the hit rate calculating section 670, the controller 1200, etc. The "specified value holding means" is realized by the specified value holding section 680. The "data protection means" is mainly realized by a non-volatile memory (or magnetic recording disk 510) or the like not shown in this figure. The time holding means is realized by the magnetic recording disk 510. However, since the respective parts operate in close cooperation, the above-mentioned correspondence with the claims is not strict. .

The outline of the read operation will be described. When a read command is received from the host via the interface controller 100, the cache control unit 660 determines whether there is target data in the cache 300 or not. At the same time, the hit rate calculation unit 670 obtains and holds the hit rate.

In case of cache read hit, DMA6
20 reads the target data from the cache 300 and transfers it to the interface controller 100.

In the case of a cache read miss, the interrupt controller 650 notifies the controller 1200 of
Notify that a cache read miss has occurred. When the controller 1200 receives this interrupt signal, the hard disk controller 1100 receives the magnetic recording disk 510.
(Note: not shown in FIG. 10) command to read data from. The data read from the magnetic recording disk 510 is sent to the interface controller 100 via the DMA 630 and the DMA 620, and is held in the cache 300 via the cache interface 610. The cache control unit 660 controls the data storage algorithm at this time.

Next, the write operation will be described. When a write command is received from the host via the interface controller 100, the cache control LSI 600
Receives data using FIFO 625. And
When a write cache is provided in the cache 300, the data is temporarily stored in the cache 300 via the cache interface 610. afterwards,
Data is transferred to the hard disk controller (HDC) 1100 through the DMA 630 in accordance with the above four timings, and data is written to the magnetic recording disk 510. Incidentally, at the time of the write operation, the magnetic recording disk 51 has already been
When data can be immediately written to 0 (that is, in normal mode), the cache 3
No. 00 at the same time as writing to the magnetic recording disk 510. In this case, although the data is immediately written to the magnetic recording disk 510, the data is also stored in the cache 300 in order to prepare for the possibility that the data will be read next. Is.

On the other hand, when the write cache is not provided, the data is immediately transferred to the hard disk controller 1100 and written on the magnetic recording disk 510. The cache control unit 660 controls the data storage algorithm at this time.

The user can rewrite the data in the specified value holding unit 680 through the MPU interface 640. Also, the current hit rate in the hit rate calculation unit 670 can be read through the MPU interface 640. Cash control unit 66
For 0, the current hit rate is always compared with the numerical value of the specified value holding unit 680. The current hit rate is the specified value holding unit 680
When it exceeds the value stored in (Note: Corresponding to the spindle motor stop regulation value), the cache control unit 660.
Causes the interrupt control unit 650 to generate an interrupt signal. Upon receiving this interrupt signal, the controller 120
0 issues a command to the power supply controller 400 to control the operation mode similar to that of the above-described embodiment. For example, the mode is changed to the low power consumption mode and the spindle motor is stopped. Other operations / processing (for example, power ON /
Also in the case of saving / reproducing the hit ratio at the time of OFF), although there is a part in which the operation main body to be executed and the specific operation are different from those in the above-described embodiment, the purpose and content thereof are basically the same as those in the above-mentioned embodiment. Is. Here, each unit may appropriately share and execute an operation not specifically described. As long as the purpose of each operation can be achieved, the operation subject etc. may be any part. Further, here, the operation is described on the premise of the first method among the above-mentioned four kinds of operation mode control methods, but other methods (second to fourth operation mode control methods) are used. When applied, the purpose and contents of the basic operation are the same as those described in the first embodiment. However, it goes without saying that the functions and configurations of the respective parts are changed / added / deleted according to the functions required for each method.

If the interrupt signal generated by the interrupt control unit 650 is directly connected to the power supply controller 400 to control the operation mode,
The burden on the controller 1200 can also be reduced.
However, in this case, the above-mentioned operation mode definition table is included in the power supply controller 400.
Also in this embodiment, similarly to the first embodiment, it is possible to achieve both reduction of power consumption and prevention of lowering of throughput.

Next, as a third embodiment, an example in which the present invention is implemented by sharing the role with the host computer side connected to the disk device will be described.

FIG. 12 shows the internal structure of the host computer 2000.

Note that these configurations may be realized as hardware, or may be realized by storing them as software and executing them.

In the system of this embodiment, the interface 2 is provided between the host computer 2000 and the disk device 2900.
It is configured by connecting at 800.

The host computer 2000 has a main memory 2
100, a command execution unit 2200, and a host interface unit 2300.

The cache 211 is stored in the main memory 2100.
0 is provided. Further, in the main memory 2100,
Hit ratio holding unit 2120, access count holding unit 213
0, hit count holding unit 2140, specified value holding unit 215
0, a mode storage unit 2160 is also provided. These correspond to the cache 300, the hit rate holding unit 200, and the specified value holding unit 210 in the first embodiment.

The mode storage unit 2160 is for storing the operation mode of the disk device at that time. The initial value of the mode storage unit 2160 is initialized as "normal mode" when the disk device is powered on. After that, it is rewritten every time the operation mode of the disk device 2900 is changed.

In addition, the cache presence / absence determining unit 2210 for determining whether or not the cache is hit, the hit ratio calculating unit 2220 for calculating the hit ratio, the hit ratio and the spindle motor stop regulation value are compared. Hit rate determination unit 2
230, a mode change command issuing unit 2240 for issuing a mode change command to the disk device 2900, and a cache control unit 2 for controlling the cache 300.
250, and a command execution unit 2200 that executes various processes by executing software.

Claims 4 and 11
The "cache management means" mentioned in the section is mainly
It is realized by the cash control unit 2250. The “access count holding unit” is realized by the access count holding unit 2130, the “hit count holding unit” is realized by the hit count holding unit 2140, and the “hit ratio holding unit” is realized by the hit ratio holding unit 2120. The “determination means” is mainly realized by the cache presence / absence determination unit 2210. The “hit rate calculation means” is mainly realized by the hit rate calculation unit 2220. The "operation mode control means" is mainly realized by the hit rate determination unit 2230, the mode change command issuing unit 2240, and the mode storage unit 2160. The “specified value holding means” is realized by the specified value holding unit 2150. However, since each unit operates in close cooperation, the above-described correspondence with the claims is not strict. Further, it is necessary to change the configuration as will be described later, depending on which of the above four methods is used as the operation mode control method. And, of course, there is a part in which the correspondence relationship with the claims changes accordingly.

The disk device 2900 to which this embodiment is applied has a plurality of operation modes on the side of the disk device 2900, and the operation mode can be changed by a command from the host 2000. Is assumed. As such a disk device, for example, a PC / AT (PC
/ AT is International Busines
s Machines Corporation is a registered trademark) There is already a device with an interface 2800. Therefore, a detailed description thereof will be omitted here.

In this embodiment, the following description will be made on the assumption that the low power consumption mode and the normal mode are the same as those in the first embodiment.

The outline of the read operation will be described. here,
The case where the above-mentioned first method is used as the operation mode control method will be described.

When a read operation to the disk device 2900 occurs, the cache presence / absence determining unit 2210 confirms whether the data already exists in the cache 2100. De-
If there is a cache read hit, there is a cache read hit, and if there is no cache cache miss.

The hit ratio calculation unit 2220 sequentially calculates the hit ratio and stores it in the cache unit 2110.

When the hit rate becomes higher than a preset value (Note: this value corresponds to the above spindle motor stop regulation value), the hit rate determination unit 2230 determines that the hit rate is higher than the preset value.
This is notified to the mode change command issuing unit 2240.
Then, the mode change command issuing unit 2240 issues a command to the disk device 2900 so as to shift to the low power consumption mode. For example, the disk device 2
900 is the interface 2800, and the above-mentioned PC /
If you have an AT interface,
The command E0 is issued to make a transition to the mode.

The mode change command is transmitted to the disk device 2900 via the host interface 2300 and the interface 2800. As a result, the disk device 2900 shifts to the low power consumption mode (Note: in the case of PC / AT, the standby mode), and the spindle motor is stopped. The high hit rate for issuing the mode change command depends on the user.
It may be set to 00.

This processing method will be described in more detail with reference to the flowchart of FIG.

When a read command is issued (step 90)
0), the cache presence / absence determining unit 2210 determines whether or not the cache is hit (step 902). If there is a hit, the command execution unit 2200 reads the data in the cache 2110 and uses it in a desired operation or the like (step 910). Furthermore, the command execution unit 2200 uses the access count holding unit 2130,
The access count and hit count held in the hit count holding unit 2140 are incremented (step 91).
2). Then, the hit rate calculation unit 2220 calculates the hit rate using the updated access count and the like (step 914). The hit rate determination unit 2230 determines that the current hit rate calculated by the hit rate calculation unit 2220 is a specified value (=
It is determined whether or not the spindle motor stop regulation value) has been reached (step 916). If the result of determination is that the specified value has not been reached, the processing is terminated (step 9).
99). On the other hand, if the specified value is reached in step 916, the command execution unit 2220 determines that the mode storage unit 21
By checking the contents of 60, the disk device 290
The current operation mode of 0 is confirmed (step 920).
As a result, in the normal mode, the mode change command issuing unit 2240 issues a command to the disk device 2900 to shift to the low power consumption mode and stops the spindle motor (step 922). In this case,
In the above-mentioned PC / AT, the mode is changed to the standby mode. Then, the process ends (step 999).

If the cache read miss is detected in step 902, the command execution part 2220 refers to the mode storage part 2160 to confirm the current operation mode of the disk device 2900 (step 930). Normal mode
If so, the data is read from the magnetic recording disk and transferred (step 932). After that, each part
Increment of the number of accesses (step 934),
The hit ratio is calculated (step 936), and the process ends (step 999).

On the other hand, if the mode is low power consumption mode in step 930, the command execution section 2200 sends a command to the disk device 2900 to shift to the normal mode (step 940). As a result, the spindle motor is activated. In the above PC / AT, the idle mode is entered in this case.

Then, the disk device enters the "Ready" state (step 942) and waits for the disk device 2900 to transfer data (step 944). After that, the access count holding unit 2130 increments the access count (step 946), and the hit rate calculation unit 2220 calculates the hit rate (step 94).
8). Then, the process ends (step 999).

The function of returning the current operation mode in response to an inquiry from the host has a disk device 2900.
, Then the host will proceed to steps 920, 93.
At 0, the current operation mode may be inquired directly to the disk device 2900. In this case, the mode storage unit 2160 becomes unnecessary.

Also, the operation mode is changed (or maintained).
In this case, if a command designating the operation mode is always sent without confirming the operation mode,
The storage unit 2160 may be omitted. For example, in FIG.
In step 916 of 1., if the hit rate is larger than the specified value, the standby instruction may be issued. In this case, step 920
Is unnecessary.

Other operations / processing (for example, power ON
Regarding the hit rate storage / reproduction at the time of turning off / off, etc.), although the subject of the operation and the specific operation are different from those in the above-described embodiment, the content and purpose thereof are basically the same as those in the above-described embodiment. It is the same. In addition, here, 4
The operation has been described on the premise of the first method among the various operation mode control methods, but other methods (second to fourth operation modes) have been described.
When the control method) is applied, the purpose and contents of the basic operation are the same as those described in the above embodiment.
However, it goes without saying that it is necessary to add / change / delete the functions required for each method separately.

For example, when applying the second method,
As shown in FIG. 14, an f (R) computing unit 2270 for obtaining the mode transition time as a function of the hit rate, and a transition time monitoring unit corresponding to a timer for monitoring whether or not the mode transition time has elapsed 2280 is further provided. On the other hand, since the comparison between the spindle motor stop regulation value and the hit rate is not performed, the hit rate determination unit 2230 is omitted. An outline of the operation when the second operation mode control method is applied will be described. f (R) calculation unit 2270
Determines the mode transition time using the hit rate obtained by the hit rate calculation unit 2220. Transition time monitoring unit 2280
Monitors the elapsed time since the last command was issued to the disk device 2900. Then, when the mode transition time elapses, a mode change command issuing unit 2400 notifies the effect.
Make Then, the mode change command issuing unit 240
0 sends a mode change command to the disk device 2900 to set it to a low power consumption mode. For example, in the PC / AT disk device 2900, an idle command is sent to set the idle mode.

Further, when the third method is applied, as shown in FIG.
An R calculation unit 2260 is provided. When the fourth method is applied, in addition to the configuration shown in FIG. 14, a ΔR calculation unit 2260 for obtaining the slope of the hit ratio and a mode transition time g are determined.
An (R, ΔR) calculation unit 2290 is provided. On the other hand, f
(R) The calculation unit 220 is eliminated (see FIG. 16).

This embodiment can be basically realized by only the software executed by the host. Therefore, there is an advantage that it is possible to reduce power consumption and prevent lowering of throughput while using the conventional disk device as it is.

Needless to say, the present invention is not limited to a storage device using a magnetic disk or its control device. Of course, it can be applied to a storage device using an optical disk or a magneto-optical disk. Further, the present invention can be applied regardless of whether the disk serving as the storage medium is fixed or replaceable (Note: in this case, the storage medium (Note: the magnetic recording circle in the above embodiment Each time the plate 510) is replaced, it is necessary to copy the function defining the mode transition time to a newly used storage medium, or to separately provide a memory or the like for holding the mode transition time. .). Furthermore, it is also applicable when using a read-only storage medium such as a CD-ROM. Moreover,
The storage medium is not limited to the disk type. It goes without saying that the read circuit, the head (or the optical pickup), and the like are configured according to the type of storage medium used.

Further, according to the present invention, when a plurality of types of storage media (in the above embodiment, cache and magnetic disk) different in operation speed, power consumption, storage capacity, device cost, etc. are used in combination, Widely applicable. In this case, the usage of each storage medium should be decided depending on which of the operating speed, power consumption and the like is important in designing the device. Further, the specific values such as the above-mentioned spindle motor stop regulation value are also determined depending on which of these points is emphasized. For example, when the magnetic tape storage device and the magnetic disk device are used in combination, if importance is attached to the throughput, the magnetic disk device having a high operation speed is used as the cache in the above embodiment, while the operation is performed. It seems preferable to use a slow magnetic tape storage device as the magnetic disk device in the above embodiment. In addition, if it is more important to prevent the throughput from decreasing, the spindle motor stop regulation value is set to a large value, and conversely, if more importance is attached to the suppression of power consumption, the spindle motor is stopped. Set a smaller stop limit value.

In the above description, the operation mode is controlled by using the rate of cache "hits".
It is possible to achieve substantially the same control using the cache "miss" rate. Further, the definition of the “hit rate” is not limited to the above-mentioned definition, and may be any as long as it indicates a possibility that the cache is substantially hit.

[0152]

As described above, according to the present invention,
When the low power consumption mode is used, it is possible to minimize the decrease in throughput. For example, since the spindle motor is stopped in accordance with the value of the hit rate or the trend of the change in the hit rate, the number of times the spindle motor is started can be reduced. This makes it possible to reduce power consumption by stopping the spindle motor and achieve high-speed processing of recorded data. This is particularly effective in the field of small disk devices that require low power consumption.

Furthermore, by additionally providing a write cache when the spindle motor is stopped, the number of times the spindle motor is restarted due to a write operation can be reduced, and the processing time can be greatly shortened. Further, the operating time of the mechanical system (HDA) can be reduced and the life of the device can be extended.

[Brief description of drawings]

FIG. 1 is a configuration diagram when the present invention is applied to a magnetic disk device.

FIG. 2 is a diagram showing an example of an operation mode definition table.

FIG. 3 is a graph showing how a cache hit rate changes with respect to disk usage time.

FIG. 4 is a diagram showing a specified value setting command when the interface is SCSI.

FIG. 5 is a diagram showing a hit rate read command when the interface is SCSI.

FIG. 6 is an operation mode using a spindle motor stop specified value.
It is a flow chart which shows the processing contents in the method (1st method) of controlling mode.

FIG. 7 is a graph showing an example of a function f (R) of the mode transition time used in the method (second method) of changing the mode transition time according to the hit rate.

FIG. 8 is a flowchart showing the processing contents in the second method.

FIG. 9 is a graph showing an example of a function f (R) of mode transition time used in the method (fourth method) of changing the mode transition time according to the hit rate and the slope of the hit rate.

FIG. 10 is an overall configuration diagram showing a second embodiment.

11 is an internal block diagram of a cache control LSI 600. FIG.

FIG. 12 is a system configuration diagram showing a third embodiment.

FIG. 13 is a flowchart showing the processing of the host in the third embodiment.

FIG. 14 is a diagram showing the internal configuration of the host when the second method is applied as the operation mode control method.

FIG. 15 is a diagram showing a configuration in a host when a third method is applied as an operation mode control method.

FIG. 16 is a diagram showing a configuration in a host when a third method is applied as an operation mode control method.

FIG. 17 is a transition block diagram of operation modes in a conventional disk device.

[Explanation of symbols]

100 ... Interface controller, 110 ... Hard disk controller (HDC), 120 ... Controller, 130 ... R / W (read / write) circuit,
140 ... Positioning control circuit, 150 ... Spindle motor control circuit, 200 ... Hit ratio holding unit, 210 ... Specified value holding unit, 300 ... Cache, 310 ... Nonvolatile memory, 400 ... Power control controller, 500 ... Magnetic disk drive mechanism unit (HDA), 510 ... Magnetic recording disk, 520 ... Spindle motor, 530 ... Magnetic head, 540 ... Actuator, 600 ... Cache control LSI, 610 ... Cache interface, 620 ... DMA, 625 ... FIFO (Fi
rst In First Out Memory),
630 ... DMA, 635 ... FIFO, 640 ... M
PU interface, 650 ... Interrupt controller, 660 ... Cache control unit, 670 ...
Hit rate calculation unit, 680 ... Specified value holding unit, 2000
... host computer, 2900 ... disk device,
2800 ... Interface

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hitoshi Ogawa 292 Yoshida-cho, Totsuka-ku, Yokohama City, Kanagawa Prefecture Hitachi Ltd. Microelectronics Device Development Laboratory (72) Inventor, Fukai Oi 2880, Kozu, Odawara, Kanagawa Prefecture House number Hitachi Ltd. Odawara factory

Claims (15)

[Claims] 1. A storage device having a plurality of operation modes and using a main storage medium and a cache storage medium as a storage medium, accepts an instruction from another device, and executes the instruction. Input / output means for exchanging data with other required devices, main memory reading means for reading the data stored in the main storage medium, and data read by the main memory reading means A cache management means having a function of storing in the cache storage medium and a function of reading data stored in the cache storage medium, counting the number of times a read command is received from another device,
Access count holding means for holding as the access count, judging means for judging whether or not the data which is the target of the read command from another device is stored in the cache storage medium, and judgment by the judging means As a result, hit count holding means for counting the number of times the data to be read is held in the cache storage medium and holding it as the hit count, and hitting using the hit count and the access count A hit rate calculating means for calculating a rate, a prescribed value holding means for retaining a preset first prescribed value, which is a reference for changing the operation mode, and a latest hit rate calculated by the hit rate calculating means. The operation mode is compared with the first prescribed value and the operation mode is determined according to the result of the comparison.
And an operation mode control means for controlling the mode, wherein the operation mode control means has, as the operation mode, at least access to the main storage medium and access to the cache storage medium. A first mode capable of performing access and a second mode consuming less power than the first mode and capable of accessing at least the cache storage medium.
At least two modes are provided, and as a result of the comparison, if the hit rate is smaller than the first specified value, the operation mode of the storage device is set to the first mode.
If the hit rate is larger than the first specified value, the operation mode of the storage device is changed to the second mode.
A storage device characterized by being transferred to a mode. 2. A slope for obtaining a slope of a change in hit rate at the present time by using a hit ratio holding unit that stores a hit ratio in at least a certain past range from the present time and a value of the hit ratio stored in the hit ratio holding unit. Calculating means, the specified value holding means further has a second specified value set in advance, and the operation mode control means sets the slope of the hit rate change calculated by the slope calculating means. , Further having a function of comparing with the second prescribed value, and even when the hit rate is larger than the first prescribed value, when the inclination is smaller than the second prescribed value, the operation mode is changed. 2. The storage device according to claim 1, wherein the mode is not transferred to the first mode. 3. A memory comprising a main memory means for storing data and a cache memory means for holding the data read from the main memory means, and a memory having a plurality of operation modes. In the control method of the device, the hit rate is compared with a preset specified value, and as a result of the comparison, if the hit rate is smaller than the specified value, at least the data in the main storage means is read. And the storage of data in the cache memory means in an operation mode capable of performing the above operation. When the hit rate is larger than the specified value, the power consumption is higher than that in the first mode. A method of controlling a storage device, characterized in that the number of operations is small and at least the operation mode is such that the data can be read from the cache storage means. 4. A cache storage medium for storing data in a control device of a storage device having a plurality of operation modes and having a function of changing the operation mode according to an external command. A cache management means having a function of storing the data output from the storage device in the cache storage medium and a function of reading the data stored in the cache storage medium; and a read command for the storage means. An access number holding means for counting the number of times and holding it as an access number, a determination means for determining whether or not the data to be read is stored in the cache storage medium, and a determination by the determination means. As a result, the number of times the data to be read is held in the cache storage medium is counted as the hit number. Hit number holding means for holding, hit rate calculation means for calculating the hit rate using the hit number and the access number, specified value holding means for holding a preset specified value, the hit rate and the above An operation mode control means for comparing an operation mode of the storage device according to a result of the comparison with a specified value, and a control device for the storage device. 5. A storage device having a plurality of operation modes and using a main storage medium and a cache storage medium as a storage medium, accepts an instruction from another device, and executes the instruction. Input / output means for exchanging data with other required devices, main memory reading means for reading the data stored in the main storage medium, and data read by the main memory reading means To the cache storage medium and a function to read the data stored in the cache storage medium, and the number of times a read command is received from another device is counted as the access count. The access number holding means for holding and whether or not the data which is the target of the read instruction from the other device is stored in the cache storage medium. Determining means for determining the number of times the data to be read is held in the cache storage medium as a result of the determination by the determining means, and a hit number holding means for holding the number of hits as the number of hits; A hit ratio calculating means for calculating a hit ratio using the hit count and the access count, and an operation mode from the last access from another device.
The mode transition time holding means for storing a predefined correspondence between the time until the mode is changed (hereinafter referred to as "mode transition time") and the hit rate, and the current mode transition time Specified value holding means to hold, time measuring means to measure the elapsed time from the last access from another device, hit rate at the present time, hit rate held in the mode transition time holding means From the correspondence between the mode transition time and the mode transition time, the mode transition time at the present time is obtained and stored in the specified value holding means, and the mode transition time at the present time and the elapsed time are compared, An operation mode control means for controlling the operation mode according to the result of the comparison, wherein the operation mode control means includes at least access to the main storage medium and the cache storage medium. And access to, the first mode can be carried out - and de, the first mode - Doyori also consumes less power, and the second that is accessible to at least said cache memory medium
At least two operation modes, that is, the operation mode of the memory device is set to the above-mentioned operation mode when the elapsed time exceeds the mode transition time as a result of the comparison. A storage device characterized by being transferred to two modes. 6. A slope calculation for obtaining a slope of a change in hit rate at the present time by using hit rate holding means for storing hit rates in a certain range in the past from the present time and a value of the hit rate stored in the hit rate holding means. Means, and the predefined correspondence relationship between the mode transition time and the hit rate held by the mode transition time holding means is
It is defined including the correspondence with the slope of the change in the hit rate, and the operation mode control means performs the processing for obtaining the mode transition time in the hit rate and the slope of the hit rate at the present time. And the mode held by the mode transition time holding means.
6. The storage device according to claim 5, wherein the correspondence relationship between the transition time, the hit rate, and the slope of the change in the hit rate is used. 7. A memory having a main memory means for storing data and a cache memory means for holding the data read from the main memory means, and a memory having a plurality of operation modes. In the control method of the device, the hit rate is obtained by using the number of times the data to be read is held in the cache storage means and the number of times the read command is received, and the hit rate and a predefined function The mode transition time is determined on the basis of the above, and at least the reading of the data of the main memory means and the above-mentioned mode transition time until the mode transition time elapses after the last access from another device. Data to cache storage means
Data is stored in the first mode capable of storing and storing the data, and after the mode transition time has elapsed since the last access from another device, the power consumption is higher than that in the first mode. And a second mode in which at least data can be read from the cache storage means. 8. A cache storage medium for storing data in a control device of a storage device having a plurality of operation modes and having a function of changing the operation mode according to an instruction from the outside. A cache management means having a function of storing the data output from the storage device in the cache storage medium and a function of reading the data stored in the cache storage medium; and a read command for the storage means. An access number holding means for counting the number of times and holding it as an access number, a determination means for determining whether or not the data to be read is stored in the cache storage medium, and a determination by the determination means. As a result, the number of times the data to be read is held in the cache storage medium is counted as the hit number. A hit number holding means for holding, a hit rate calculating means for calculating a hit rate using the hit number and the access number, and a function defined in advance between the hit rate and the mode transition time are held. A mode transition time holding means, a specified value holding means for holding the current mode transition time, and a time counting means for measuring an elapsed time from the last access to the storage device, From the hit rate at the present time and the correspondence relationship between the hit rate held in the mode transition time holding means and the mode transition time, the mode transition time at the present time is obtained and stored in the prescribed value holding means. At the same time, the mode transition time at the present time is compared with the elapsed time. As a result of the comparison, if the elapsed time exceeds the mode transition time, the storage device is A control device for a storage device, characterized in that the operation mode of the storage device is changed. 9. The hit rate calculation means calculates the hit rate each time the read command is received from another device, and the operation mode control means calculates the hit rate. 6. The storage device according to claim 1, wherein the comparison is performed every time it is read. 10. The main memory read means reads data from the main storage medium by using magnetic or optical, and the cache management means electrically reads data from the cache storage medium. 7. The storage device according to claim 1, wherein the storage device reads data. 11. A storage device according to claim 1, further comprising the main storage medium and the cache storage medium. 12. When the power is turned off, at least the data stored in the cache storage medium, the access count held in the access count holding means, and the hit count holding means are held. 6. The storage device according to claim 1, further comprising a data protection unit that stores and protects the number of hits. 13. The data protection means protects the protected data in the cache storage medium and the protected hit count in the hit count holding means when the power is turned on. 13. The storage device according to claim 12, wherein the number of times of access being performed is stored in the access number holding means. 14. A storage device that uses a disk-type main storage medium and a cache storage medium as a storage medium, accepts an instruction from another device, and executes another instruction that is necessary when the instruction is executed. Input / output means for exchanging data with the device, main memory reading means for reading data from the main memory medium, and data read by the main memory reading means are stored in the cache memory medium. Cache management means having a function and a function of reading data stored in the cache storage medium; and data from another device when the main storage medium is not in a rotation state in which the data can be read. When a data read command is received, it is determined whether the data is stored in the cache storage medium, and if it is stored, the manual storage medium is started. And a control unit that reads out and outputs the data stored in the cache storage medium without moving. 15. A storage device, which uses a disk-type main storage medium and a write cache storage medium as a storage medium, accepts an instruction from another device, and is necessary when the instruction is executed. I / O means for exchanging data with the device, main memory writing means for writing data to the main storage medium, and when the main storage medium is not in a rotation state in which data can be written. When a data write command is received from another device, the data is stored in the write cache storage medium, and at the time when the data is written in the write cache storage medium, the write command is written. The execution is notified to the other device, and thereafter, the data written in the write cache storage medium at the preset timing is transferred to the hand storage medium. Storage apparatus characterized by and a control means for writing the.