JP7572520B1 - STORAGE APPARATUS, STORAGE CONTROL METHOD, AND PROGRAM - Google Patents

Abstract

[Problem] One of the objectives is to provide a storage device or the like capable of suppressing degradation of processing performance. [Solution] A storage device according to one aspect of the present disclosure has a first memory which is a non-volatile storage medium, and a second memory which is a non-volatile storage medium having a processing speed slower than that of the first memory, and is equipped with a calculation means for calculating the usage frequency of data stored in a first storage area constructed in the first memory, a determination means for determining whether the data is used frequently based on the calculated usage frequency, and a data control means for writing data determined to be used infrequently to a second storage area constructed in the second memory. [Selected Figure] Figure 1

Description

This disclosure relates to storage control technology.

Technology relating to storage devices is disclosed in Patent Document 1.

Patent Document 1 discloses an SSD (Solid State Drive) having a high-speed nonvolatile memory and a low-speed nonvolatile memory. Specifically, the SSD disclosed in Patent Document 1 stores received data in the high-speed nonvolatile memory. At this time, data determined to be hot data is stored in the high-speed nonvolatile memory, and data determined to be cold data is moved from the high-speed nonvolatile memory to the low-speed nonvolatile memory. Note that hot data is data that is write-accessed frequently. Cold data is data that is written once or infrequently and read frequently.

JP 2009-48613 A

The frequency of data usage may change. For example, suppose that certain data is stored in a low-speed non-volatile memory because it is used infrequently. Later, the frequency of use of the certain data may increase. In this case, the certain data will be managed in the low-speed non-volatile memory. In other words, even if the certain data is used frequently, access to the certain data will be made to the low-speed non-volatile memory. This may lead to a decrease in the processing performance of storage devices such as SSDs.

This disclosure was made in consideration of the above-mentioned problems, and one of its objectives is to provide a storage device etc. that can suppress a decrease in processing performance.

A storage device according to one aspect of the present disclosure has a first memory which is a non-volatile storage medium, and a second memory which is a non-volatile storage medium having a processing speed slower than that of the first memory, and is equipped with a calculation means for calculating the usage frequency of data stored in a first storage area constructed in the first memory, a determination means for determining whether the data is used frequently based on the calculated usage frequency, and a data control means for writing data determined to be used infrequently to a second storage area constructed in the second memory.

A storage control method according to one aspect of the present disclosure, in a storage device having a first memory, which is a non-volatile storage medium, and a second memory, which is a non-volatile storage medium having a processing speed slower than that of the first memory, calculates the frequency of use of data stored in a first storage area constructed in the first memory, determines whether the data is used frequently based on the calculated frequency of use, and writes data determined to be used less frequently to a second storage area constructed in the second memory.

A program according to one aspect of the present disclosure causes a computer to execute the following processes in a storage device having a first memory, which is a non-volatile storage medium, and a second memory, which is a non-volatile storage medium having a slower processing speed than the first memory: calculating the frequency of use of data stored in a first storage area constructed in the first memory; determining whether the data is used frequently based on the calculated frequency of use; and writing data determined to be used infrequently to a second storage area constructed in the second memory.

This disclosure makes it possible to suppress degradation of processing performance.

FIG. 2 is a diagram illustrating an example of a functional configuration of a storage device according to the present disclosure. 11 is a flowchart illustrating an example of an operation of the storage device according to the present disclosure. 1 is a block diagram including an example of a functional configuration of a storage device 100 according to the present disclosure. FIG. 2 is a block diagram showing an example of a hardware configuration of a storage device according to the present disclosure. FIG. 13 is a diagram illustrating an example of a management table according to the present disclosure. FIG. 13 is a diagram illustrating an example of a usage frequency table according to the present disclosure. 1 is a first flowchart illustrating an example of an operation of a storage device according to the present disclosure. 11 is a second flowchart illustrating an example of an operation of the storage device according to the present disclosure.

Embodiments of the present disclosure will be described below with reference to the drawings. Note that in this disclosure, each of the drawings is associated with one or more embodiments.

First Embodiment
An overview of the storage device of the first embodiment will be described.

Figure 1 is a diagram showing an example of the functional configuration of a storage device 100. The storage device 100 includes a non-volatile storage medium. For example, the storage device 100 is configured with an SSD.

As shown in FIG. 1, the storage device 100 has a first memory 10 and a second memory 20. The first memory 10 and the second memory 20 are non-volatile storage media. For example, the first memory 10 and the second memory 20 are each a flash memory. The first memory 10 is a memory with higher processing performance than the second memory 20. For example, the first memory 10 is a memory with a faster processing speed than the second memory 20. Conversely, the second memory 20 is a memory with a slower processing speed than the first memory 10. Furthermore, the first memory 10 may be a memory with a higher number of writable times than the second memory 20. In other words, the first memory 10 may be a memory with a higher write durability than the second memory 20.

Data stored in the storage device 100 is written to a memory area constructed by the first memory 10 or the second memory 20. The memory area constructed by the first memory 10 is referred to as the first memory area. The memory area constructed by the second memory 20 is referred to as the second memory area.

The reference process of data stored in the first memory 10 is faster than the reference process of data stored in the second memory 20. Therefore, by managing a large amount of data in the first memory 10, the reference process speed of the storage device as a whole is improved. On the other hand, there is a limit to the number of writes in each memory. Therefore, if data is managed only in the first memory 10, there is a risk that the time until the limit on the number of writes in the first memory 10 is reached will be shortened. Therefore, it is conceivable to manage data with a high number of references in the first memory 10 and data with a low number of references in the second memory 20. This makes it possible to speed up processing in the storage device as a whole and to prevent the time until the limit on the number of writes is reached from being shortened.

As shown in FIG. 1, the storage device 100 includes a calculation unit 110, a determination unit 120, and a data control unit 130. The calculation unit 110 calculates the usage frequency of data stored in the storage device 100. For example, data is stored in a first storage area constructed by a first memory. The data is referenced, for example, by a request from an external device. The calculation unit 110 may calculate the number of times the data is referenced per unit time as the usage frequency.

In this manner, the calculation unit 110 calculates the usage frequency of the data stored in the first storage area constructed in the first memory 10. The calculation unit 110 is an example of a calculation means.

The determination unit 120 determines whether the frequency of use of the data is high or low. For example, the determination unit 120 compares the calculated frequency of use with a threshold value. Then, if the frequency of use is equal to or higher than the threshold value, the determination unit 120 may determine that the frequency of use of the data is high. Also, if the frequency of use is lower than the threshold value, the determination unit 120 may determine that the frequency of use of the data is low.

In this way, the determination unit 120 determines whether the data is used frequently based on the calculated frequency of use. The determination unit 120 is an example of a determination means.

The data control unit 130 controls the data stored in the first storage area or the second storage area. Specifically, the data control unit 130 writes data stored in the first storage area that is determined to be used infrequently to the second storage area. As a result, the data determined to be used infrequently is present in both the first storage area and the second storage area.

In this way, the data control unit 130 writes data determined to be used infrequently to the second storage area constructed in the second memory 20. The data control unit 130 is an example of a data control means.

Next, an example of the operation of the storage device 100 will be described with reference to FIG. 2. Note that in this disclosure, each step in the flowchart will be represented by a number assigned to each step, such as "S1."

Figure 2 is a flowchart explaining an example of the operation of the storage device 100. The calculation unit 110 calculates the usage frequency of the data stored in the first storage area constructed in the first memory 10 (S1). The determination unit 120 determines whether the data is used frequently based on the calculated usage frequency (S2). The data control unit 130 writes the data determined to be used infrequently to the second storage area constructed in the second memory 20 (S3).

Thus, the storage device 100 of the first embodiment has a first memory 10, which is a non-volatile storage medium, and a second memory 20, which is a non-volatile storage medium with a slower processing speed than the first memory. The storage device 100 also calculates the usage frequency of data stored in a first storage area constructed in the first memory 10. The storage device 100 determines whether the data is used frequently based on the calculated usage frequency. The storage device 100 then writes data determined to be used infrequently to a second storage area constructed in the second memory 20.

The frequency of data usage may change. For example, the frequency of use of data managed in the second memory 20 may increase. In this case, continuing to manage the data in the second memory 20 may lead to a decrease in the processing performance of the device as a whole. In response to this, the storage device 100 stores data determined to be used infrequently in both the first memory 10 and the second memory 20. Therefore, if the frequency of use of data managed in the second memory 20 increases, the storage device 100 can switch the management of the data to the first memory 10. This allows the storage device 100 to suppress a decrease in processing performance.

Second Embodiment
Next, a storage device according to a second embodiment will be described. In the second embodiment, a further example of the storage device 100 described in the first embodiment will be described. Note that some of the contents overlapping with the first embodiment will not be described.

[Details of storage device 100]
3 is a block diagram including an example of a functional configuration of the storage device 100. In this example, the storage device 100 is communicably connected to a host device 200. The host device 200 is a computer capable of inputting and outputting data. The host device 200 is capable of accessing the storage device 100. For example, the host device 200 transmits a data read request or a data write request to the storage device 100. As a result, the host device 200 obtains data from the storage device 100 and stores data in the storage device 100.

The storage device 100 performs a data read process or a data write process in response to a request from the host device 200. The storage device 100 has at least a first memory 10 and a second memory 20. That is, the storage device 100 accesses a first storage area constructed by the first memory 10 or a second storage area constructed by the second memory 20 in response to a request from the host device 200. The storage device 100 then performs a data read process or a data write process. Note that the memory that the storage device 100 has is not limited to this example. The storage device 100 may have an additional memory. The storage device 100 may then perform a read process or a write process on the data stored in the storage area constructed by the additional memory.

FIG. 4 is a block diagram showing an example of the hardware configuration of a storage device according to the present disclosure. The storage device and storage control method described in this disclosure are realized, for example, by a device having the hardware configuration shown in FIG. 4. The storage device 100 is configured, for example, in an SSD. In the example of FIG. 4, the storage device 100 includes an interface 1, a controller 2, a buffer memory 3, a first memory element group 4, and a second memory element group 5. The storage device 100 may be realized by multiple electric circuits.

The interface 1 connects the storage device 100 and the host device 200. The interface 1 may be implemented using standards such as IDE (Integrated Device Electronics), SATA (Serial Advanced Technology Attachment), and PCIe (Peripheral Component Interconnect express).

The controller 2 performs various controls related to data. For example, the controller 2 performs data read and write processes on the first memory element group 4 and the second memory element group 5.

The buffer memory 3 is a storage medium that temporarily stores data. The buffer memory 3 may be composed of, for example, a dynamic random access memory (DRAM).

The first memory element group 4 and the second memory element group 5 are non-volatile storage media that store data. The first memory element group 4 and the second memory element group 5 are, for example, NAND-type flash memories. The first memory element group 4 has first memory elements 41-1, 41-2, ..., 41-n (n is a natural number). In other words, the first memory element group 4 may have multiple first memory elements. In this example, n first memory elements are connected in series.

The second memory element group 5 has second memory elements 51-1, 51-2, ..., 51-m, ..., 5p-1, 5p-2, ..., 5p-m (m and p are natural numbers). The second memory element group 5 may have multiple second memory elements. In this example, there are p sets of second memory elements connected in series.

The first memory element group 4 may function as the first memory 10 in the present disclosure. Also, the second memory element group 5 may function as the second memory 20 in the present disclosure. That is, the first memory area may be constructed in the first memory element group 4. Also, the second memory area may be constructed in the second memory element group 5.

The first memory element group 4 and the second memory element group 5 are storage media with different performance. For example, the first memory element group 4 has a faster processing speed than the second memory element group 5. Also, for example, the first memory element group 4 has a higher write durability than the second memory element group 5. Also, for example, the first memory element group 4 has a smaller storage capacity than the second memory element group 5.

Each component in the functions of the storage device of the present disclosure may be realized, for example, in the controller 2. Alternatively, each component may be realized as a further component connectable to the first memory element group 4 and the second memory element group 5. There are various variations in the method of realizing the storage device. For example, each component included in the storage device may be realized as a dedicated device. Furthermore, the storage device may be realized based on a combination of multiple devices.

Also included in the scope of each embodiment is a processing method in which a program for realizing each configuration in the functions of each embodiment of the present disclosure is recorded on a specified storage medium, the program recorded on the specified storage medium is read as code, and executed on a computer. That is, a computer-readable storage medium is also included in the scope of each embodiment. Also included in each embodiment are a storage medium on which the above-mentioned program is recorded, and the program itself. The specified storage medium is, for example, a floppy (registered trademark) disk, a hard disk, an optical disk, a magneto-optical disk, a CD (Compact Disc)-ROM, a magnetic tape, a non-volatile memory card, or a ROM, but is not limited to these examples. Also included in the scope of each embodiment is a program recorded on the specified storage medium that is not limited to a program that executes processing by itself, but also includes a program that operates on an OS (Operating System) to execute processing in cooperation with other software or functions of an expansion board.

As shown in FIG. 3, the storage device 100 includes a calculation unit 110, a determination unit 120, a data control unit 130, and an access control unit 140.

The access control unit 140 accesses data in response to a request from the host device 200. Specifically, the access control unit 140 receives a request to read or write data from the host device 200. A read request is sometimes called a read command. A write request is sometimes called a write command. Each request includes information corresponding to the request.

For example, a write request includes address information and the data to be written. The address information is information indicating the data location. The address information may be information based on LBA (Logical Block Addressing), for example. When the access control unit 140 receives a write request, it writes the data included in the write request to the first storage area. Furthermore, the write request may include a command number indicating the type of write operation and information on the time when the write was performed.

In this way, in response to a write request from the host device 200, the access control unit 140 may first write data to the first storage area.

The read request also includes address information. When the access control unit 140 receives a read request, it reads data from a location in the storage area that corresponds to the address information included in the read request.

Here, the address information and a position in the storage area are associated with each other. Information indicating a position in the storage area is called position information. For example, the access control unit 140 may use a management table to access a position in the storage area that corresponds to the address information. The management table is information in which address information and position information are associated with each other.

Figure 5 is a diagram showing an example of a management table. In the example of Figure 5, the management table contains information that associates address information, location information of the first storage area, location information of the second storage area, and management information. For example, the record in the first row indicates that data of address information "A1" is stored in location information "X1", which is a position in the first storage area, and is not stored in the second storage area. For example, when the access control unit 140 receives a read request that includes address information "A1", it reads the data of location information "X1".

In the example of FIG. 5, the record on the second line indicates that the data of address information "A2" is stored in location information "X2" in the first storage area and location information "Y2" in the second storage area. The management information also indicates "Y2". Here, management information is information that indicates the location where data is managed. In this example, the data of address information "A2" is managed in location information "Y2" in the second storage area. Therefore, for example, when the access control unit 140 receives a read request that includes address information "A2", it reads the data of location information "Y2".

When a write request is made by the host device 200, the access control unit 140 writes the data included in the request to a position in the first storage area that corresponds to the address information included in the request. The access control unit 140 then updates the management table. For example, it is assumed that the address information included in the write request is "A4". It is also assumed that the access control unit 140 has written the data to the position information "X4" in the first storage area. At this time, the access control unit 140 updates the management table so that the address information "A4" corresponds to the position information "X4" in the first storage area. At this time, the access control unit 140 corresponds the management information indicating "X4" to the address information "A4".

The management table may be stored in any storage medium of the storage device 100. For example, the management table may be stored in a storage medium included in the controller 2. Alternatively, the management table may be stored in the first memory 10 or the second memory 20. Alternatively, the management table may be stored in a further component having the functionality of a storage medium.

In this way, the access control unit 140 accesses data in the first storage area or the second storage area in response to a request from the host device 200. The access control unit 140 is an example of an access control means.

The calculation unit 110 calculates the frequency of data usage. Specifically, the calculation unit 110 monitors the number of accesses to the data stored in the first storage area or the second storage area. For example, when a specific piece of data stored in the first storage area is read in response to a read request, the calculation unit 110 increments the number of accesses to the specific piece of data by 1. At this time, the calculation unit 110 may monitor the accesses to the specific piece of data up to a specific time ago. That is, the calculation unit 110 may calculate the number of accesses to the data from the current time to a specific time ago as the frequency of data usage. Alternatively, the calculation unit 110 may reset the number of accesses every specific time. For example, the calculation unit 110 monitors the number of accesses to the specific piece of data from a certain point in time until a specific time has elapsed. Then, after the specific time has elapsed, the calculation unit 110 may reset the number of accesses to the specific piece of data to 0. In this way, the frequency of data usage can be said to be the number of times the data is read or updated per unit time.

The storage device 100 has a usage frequency table that indicates the frequency of use of data. The usage frequency table includes information that associates information that identifies data with the frequency of use. The usage frequency table may be stored in any storage medium of the storage device 100. For example, the usage frequency table may be stored in a storage medium included in the controller 2. Alternatively, the usage frequency table may be stored in the first memory 10 or the second memory 20. Alternatively, the usage frequency table may be stored in a further component that has the functionality of a storage medium.

Figure 6 is a diagram showing an example of a usage frequency table. In the example of Figure 6, location information indicating a location in a storage area is associated with the usage frequency. In this way, location information may be used as information for identifying data. For example, the record in the first row indicates that the usage frequency for data of location information "X1" is "10". The calculation unit 110 may update the usage frequency table in accordance with the calculation of the usage frequency. For example, when data of location information "X1" is read in response to a request, the calculation unit 110 increments the usage frequency corresponding to location information "X1" by 1 to "11". Also, for example, the calculation unit 110 may update the usage frequency corresponding to location information "X1" to 0 after a predetermined time has elapsed.

The determination unit 120 determines whether the frequency of use is high or low. Specifically, the determination unit 120 compares the frequency of use calculated by the calculation unit 110 with a threshold value. For example, the determination unit 120 refers to a frequency of use table and compares each frequency of use with a threshold value. Then, for each piece of data, it is determined whether the frequency of use is high or low.

The data control unit 130 controls the data based on the result of the judgment by the judgment unit 120. Specifically, if it is judged that the data stored in the first storage area is used infrequently, the data control unit 130 writes the data to the second storage area. At this time, the data control unit 130 updates the management table.

The management table in the example of FIG. 5 shows that the data of address information "A3" is stored in position information "X3" in the first storage area. Here, it is assumed that the determination unit 120 has determined that the data of position information "X3" is used infrequently. At this time, the data control unit 130 writes, for example, the data of position information "X3" to position information "Y3" in the second storage area. Then, the data control unit 130 writes "Y3" as the position information in the second storage area corresponding to the address information "A3" in the management table. The data control unit 130 also rewrites the management information corresponding to the address information "A3" to "Y3". As a result, for example, when a read request including address information "A3" is received from the host device 200, the access control unit 140 reads the data of position information "Y3".

Also, suppose that the determination unit 120 determines that the data stored in the first storage area is frequently used. In this case, the data is managed in the first storage area. In other words, the data control unit 130 does not need to update the management table.

Alternatively, the data control unit 130 may periodically write data stored in the first storage area that is determined to be frequently used to the second storage area. For example, assume that data A that is determined to be frequently used is stored in the first storage area. In this case, the data control unit 130 may write data A to the second storage area at a predetermined time interval. The predetermined time interval is, for example, a time longer than the unit time of the frequency of use calculated by the calculation unit 110. Alternatively, the data control unit 130 may write data A to the second storage area every time data A is accessed a predetermined number of times. Note that the management table indicates the location information of the second storage area for data A. As a result, the data written to the second storage area can be used as a backup for data A.

Let us also assume that the determination unit 120 determines that the data stored in the second storage area is frequently used. At this time, the data control unit 130 controls the data to be managed in the first storage area. Specifically, the data control unit 130 updates the management table. For example, in the example of FIG. 5, the data of address information "A2" is managed in the second storage area. Then, if it is determined that the data of address information "A2" is frequently used, the data control unit 130 rewrites the management information "Y2" corresponding to address information "A2" to "X2". As a result, the access control unit 140 accesses the location information "X2" for the data of address information "A2".

[Example of Operation of Storage Apparatus 100]
Next, an example of the operation of the storage device 100 will be described with reference to FIGS.

Figure 7 is a first flowchart illustrating an example of the operation of the storage device 100. Specifically, Figure 7 shows an example of the operation of the storage device 100 when a request is made from the host device 200. The access control unit 140 receives a request from the host device 200 (S101). The access control unit 140 also accesses data in response to the request (S102).

For example, when the access control unit 140 receives a write request from the host device 200, it writes the data included in the write request to the first storage area. Then, the access control unit 140 updates the management table so that information that associates the access information included in the write request with the location information of the first storage area and management information is displayed. Also, for example, when the access control unit 140 receives a read request from the host device 200, it identifies the location of the storage area where the data is stored based on the access information included in the read request and the management table. Then, the access control unit 140 reads the data from the identified location.

The calculation unit 110 calculates the usage frequency of the data in response to the access to the data (S103). For example, the calculation unit 110 may update the usage frequency table in response to the calculation of the usage frequency.

Figure 8 is a second flowchart for explaining an example of the operation of the storage device 100. Specifically, Figure 8 is an example of the operation of the storage device 100 when determining the frequency of use. In this example of operation, the storage device 100 uses the frequency of use table updated by the example of operation in Figure 7. The determination unit 120 determines the frequency of use of data stored in the storage area. For example, the determination unit 120 determines whether the frequency of use of data is high or low, and whether the data is managed in the first storage area or the second storage area, based on the frequency of use table and the management table. If it is determined that the frequency of use of data is high ("Yes" in S201), the data is managed in the first storage area ("Yes" in S202). In this case, the storage device 100 returns to the process of S201. Note that the data in the first storage area at this time may be periodically written by the data control unit 130 to the second storage area. This allows the data written in the second storage area to be used as a backup.

If it is determined that the data is frequently used ("Yes" in S201), the data is managed in the second storage area ("No" in S202). In this case, the data control unit 130 updates the management table so that the data is managed in the first storage area (S203). Specifically, the data control unit 130 rewrites the management information corresponding to the data in the management table to the location information of the first storage area.

If it is determined that the data is used infrequently ("No" in S201), and the data is managed in the first storage area ("Yes" in S203), the data control unit 130 writes the data to the second storage area (S205). Then, the data control unit 130 updates the management table (S206).

If it is determined that the data is used infrequently ("No" in S201), and the data is managed in the second storage area ("No" in S203), the storage device 100 returns to the process of S201.

The above-described operation example is merely one example of the operation of the storage device 100. In other words, the operation of the storage device 100 is not limited to the examples in Figures 7 and 8.

In this way, the storage device 100 of the second embodiment has a first memory 10, which is a non-volatile storage medium, and a second memory 20, which is a non-volatile storage medium with a slower processing speed than the first memory. The storage device 100 also calculates the usage frequency of data stored in a first storage area constructed in the first memory 10. The storage device 100 determines whether the data is used frequently based on the calculated usage frequency. The storage device 100 then writes data determined to be used infrequently to a second storage area constructed in the second memory 20.

The storage device 100 of the second embodiment also accesses data in the first storage area or the second storage area in response to a request from the host device 200. At this time, the storage device 100 calculates the usage frequency of the specific data stored in the second storage area and determines whether the specific data is used frequently. Then, if the storage device 100 determines that the specific data is used frequently, and there is a request to access the specific data, it accesses the specific data stored in the first storage area.

The frequency of data use may change. For example, the frequency of use of data managed in the second memory 20 may increase. In this case, continuing to manage the data in the second memory 20 may lead to a decrease in the processing performance of the device as a whole. In response to this, the storage device 100 stores data determined to be used infrequently in both the first memory 10 and the second memory 20. Therefore, if the frequency of use of data managed in the second memory 20 increases, the storage device 100 can switch the management of the data to the first memory 10 without moving the data. This allows the storage device 100 to suppress a decrease in processing performance.

The storage device 100 of the second embodiment may periodically write data stored in the first storage area that is determined to be frequently used to the second storage area. This allows the storage device 100 to back up data stored in the first storage area that is determined to be frequently used.

[Modification 1]
The storage device 100 may delete stored data. For example, assume that data B is stored in the first storage area. Then, assume that it is determined that data B is used infrequently. At this time, the data control unit 130 writes data B to the second storage area. Then, the data control unit 130 may delete data B stored in the first storage area.

For example, suppose that it is determined that data B stored in the second storage area has been used infrequently for a specified period of time. In this case, the data control unit 130 deletes data B stored in the first storage area. Then, the data control unit 130 updates the management table. Specifically, the data control unit 130 deletes the location information of the first storage area corresponding to data B from the management table.

Let us assume that data B stored in the second storage area is determined to be frequently used. If data B does not exist in the first storage area, the data control unit 130 writes data B stored in the second storage area to the first storage area. Then, the data control unit 130 adds the location information of the first storage area corresponding to data B in the management table. Then, the data control unit 130 updates the management information corresponding to data B to the location information of the first storage area.

In this way, if the specified data stored in the second storage area determined to be frequently used is not present in the first storage area, the storage device 100 may write the specified data stored in the second storage area to the first storage area.

[Modification 2]
The data stored in the storage device 100 may be stored together with additional information.

For example, the access control unit 140 writes data to the first storage area in response to a write request from the host device 200. At this time, the access control unit 140 stores additional information along with the data. The additional information includes the command number indicated in the write request. The additional information may further include address information of the data and the time when the write request was made. The additional information may exist, for example, for each unit of data that is read or written. Note that the additional information is also stored when the data control unit 130 writes data from the first storage area to the second storage area.

In this manner, the data may be stored in the first storage area or the second storage area together with the additional information. The additional information may include a command number corresponding to the write request from the host device 200.

In this case, the data control unit 130 may use the additional information to check the consistency between the data in the first storage area and the data in the second storage area. For example, in the example of FIG. 5, the data with address information "A2" is managed in the second storage area. The location information in the second storage area corresponding to that data is "Y2." Here, it is assumed that it is determined that the data with location information "Y2" is used frequently.

The data control unit 130 compares the additional information of the data in the location information "Y2" in the second storage area with the additional information of the data in the location information "X2" in the first storage area. At this time, if the command numbers included in the additional information are the same, the data in the location information "Y2" and the data in the location information "X2" are the same. Therefore, if the command numbers are the same, the data control unit 130 updates the management information in the management table from "Y2" to "X2".

On the other hand, if the command numbers are not the same, the data in location information "Y2" and the data in location information "X2" are not the same. In this case, the data in location information "Y2" is newer than the data in location information "X2". Therefore, the data control unit 130 overwrites the data in location information "Y2" to location information "X2". Then, the data control unit 130 updates the management information in the management table from "Y2" to "X2".

In this way, by using additional information, the processing load required for data consistency can be reduced compared to when comparing the data itself.

The data control unit 130 may also use the additional information to repair the data. For example, assume that the access control unit 140 receives a read request from the host device 200. Then, assume that when the access control unit 140 attempts to read data from the first storage area in response to the read request, a read error occurs due to data corruption or the like. In such a case, the data control unit 130 repairs the data where the read error occurred.

Let us assume that the address information of the data where a read error occurred is "C1". The data control unit 130 compares the additional information of the data in the first storage area corresponding to the address information "C1" with the additional information of the data in the second storage area corresponding to the address information "C1". At this time, if the command numbers included in the additional information are the same, the data in the first storage area and the data in the second storage area are the same. In such a case, the data control unit 130 overwrites the data in the second storage area at the position in the first storage area corresponding to the address information "C1".

In this way, if a read error occurs when the access control unit 140 accesses specific data in the first storage area in response to a read request from the host device 200, the data control unit 130 may repair the specific data in the first storage area based on the additional information stored together with the specific data in the first storage area and the additional information stored together with the specific data in the second storage area.

The present invention has been described above with reference to the embodiments, but the present invention is not limited to the above-mentioned embodiments. Various modifications that can be understood by a person skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

The above embodiments and variations can be combined as appropriate.

Some or all of the above embodiments may be described as follows, but are not limited to the following:

<Additional Notes>

[Appendix 1]
A first memory which is a non-volatile storage medium and a second memory which is a non-volatile storage medium having a processing speed slower than that of the first memory,
a calculation means for calculating a usage frequency of data stored in a first storage area constructed in the first memory;
A determination means for determining whether the data is used frequently or not based on the calculated frequency of use;
and a data control means for writing data determined to be used infrequently into a second storage area constructed in the second memory.
Storage device.

[Appendix 2]
an access control unit that accesses data in the first storage area or the second storage area in response to a request from a host device;
The calculation means calculates a frequency of use of the predetermined data stored in the second storage area,
The determining means determines whether the predetermined data is used frequently,
when it is determined that the predetermined data is frequently used, the access control means accesses the predetermined data stored in the first storage area when there is a request for access to the predetermined data;
2. The storage device of claim 1.

[Appendix 3]
when the predetermined data determined to be frequently used is not present in the first storage area, the data control means writes the predetermined data stored in the second storage area to the first storage area;
3. The storage device of claim 2.

[Appendix 4]
the data control means periodically writes data stored in the first storage area and determined to be frequently used to the second storage area;
2. The storage device of claim 1.

[Appendix 5]
The data is stored in the first storage area or the second storage area together with additional information;
The additional information includes a command number corresponding to a write request from a host device.
5. The storage device of claim 4.

[Appendix 6]
an access control unit that accesses data in the first storage area or the second storage area in response to a request from a host device;
When a read error occurs when the access control means accesses specific data in the first storage area in response to a read request from a host device,
the data control means restores the specific data in the first storage area based on the additional information stored together with the specific data in the first storage area and the additional information stored together with the specific data in the second storage area;
6. The storage device of claim 5.

[Appendix 7]
The present invention is configured in a solid state drive (SSD) having the first memory and the second memory,
2. The storage device of claim 1.

[Appendix 8]
A storage device having a first memory which is a non-volatile storage medium and a second memory which is a non-volatile storage medium having a processing speed slower than that of the first memory,
Calculating a usage frequency of data stored in a first storage area constructed in the first memory;
Based on the calculated frequency of use, the frequency of use of the data is determined,
writing the data determined to be used infrequently into a second storage area constructed in the second memory;
Storage control methods.

[Appendix 9]
Calculating a frequency of use of the predetermined data stored in the second storage area;
determining whether the predetermined data is used frequently,
when it is determined that the frequency of use of the predetermined data is high, and when there is a request to access the predetermined data, accessing the predetermined data stored in the first storage area;
9. The storage control method according to claim 8.

[Appendix 10]
if the predetermined data determined to be frequently used is not present in the first storage area, writing the predetermined data stored in the second storage area to the first storage area;
10. The storage control method according to claim 9.

[Appendix 11]
periodically writing data stored in the first storage area and determined to be frequently used to the second storage area;
9. The storage control method according to claim 8.

[Appendix 12]
The data is stored in the first storage area or the second storage area together with additional information;
The additional information includes a command number corresponding to a write request from a host device.
12. The storage control method according to claim 11.

[Appendix 13]
When a read error occurs in accessing specific data in the first storage area in response to a read request from a host device,
recovering the specific data in the first storage area based on the additional information stored together with the specific data in the first storage area and the additional information stored together with the specific data in the second storage area;
13. The storage control method according to claim 12.

[Appendix 14]
The storage device is configured in a solid state drive (SSD) having the first memory and the second memory.
9. The storage control method according to claim 8.

[Appendix 15]
A storage device having a first memory which is a non-volatile storage medium and a second memory which is a non-volatile storage medium having a processing speed slower than that of the first memory,
A process of calculating a frequency of use of data stored in a first storage area constructed in the first memory;
A process of determining whether the data is used frequently or not based on the calculated frequency of use;
A process of writing data determined to be used infrequently into a second storage area constructed in the second memory;
to cause a computer to execute
program.

[Appendix 16]
further executing a process of accessing data in the first storage area or the second storage area in response to a request from a host device;
In the calculation process, a frequency of use of the predetermined data stored in the second storage area is calculated;
In the process of making the determination, a determination is made as to whether the predetermined data is used frequently or not;
when it is determined that the predetermined data is frequently used, in the accessing process, when there is a request for access to the predetermined data, the predetermined data stored in the first storage area is accessed;
16. The program according to claim 15.

[Appendix 17]
when the predetermined data determined to be frequently used is not present in the first storage area in the writing process, the predetermined data stored in the second storage area is written to the first storage area;
17. The program according to claim 16.

[Appendix 18]
In the writing process, data stored in the first storage area and determined to be frequently used is periodically written to the second storage area.
16. The program according to claim 15.

[Appendix 19]
The data is stored in the first storage area or the second storage area together with additional information;
The additional information includes a command number corresponding to a write request from a host device.
19. The program according to claim 18.

[Appendix 20]
further executing a process of accessing data in the first storage area or the second storage area in response to a request from a host device;
When a read error occurs in accessing specific data in the first storage area in response to a read request from a host device,
recovering the specific data in the first storage area based on the additional information stored together with the specific data in the first storage area and the additional information stored together with the specific data in the second storage area;
16. The program according to claim 15.

[Appendix 21]
The storage device is configured in a solid state drive (SSD) having the first memory and the second memory.
16. The program according to claim 15.

REFERENCE SIGNS LIST 100 Storage device 110 Calculation unit 120 Determination unit 130 Data control unit 140 Access control unit 200 Host device

Claims (7)

A first memory which is a non-volatile storage medium and a second memory which is a non-volatile storage medium having a processing speed slower than that of the first memory,
a calculation means for calculating a usage frequency of data stored in a first storage area constructed in the first memory;
A determination means for determining whether the data is used frequently or not based on the calculated frequency of use;
a data control means for writing data determined to be used infrequently into a second storage area constructed in the second memory,
the data control means periodically writes data stored in the first storage area and determined to be frequently used to the second storage area;
The data is stored in the first storage area or the second storage area together with additional information;
The additional information includes a command number corresponding to a write request from a host device.
Storage device. an access control unit that accesses data in the first storage area or the second storage area in response to a request from a host device;
The calculation means calculates a frequency of use of the predetermined data stored in the second storage area,
The determining means determines whether the predetermined data is used frequently,
when it is determined that the predetermined data is frequently used, the access control means accesses the predetermined data stored in the first storage area when there is a request for access to the predetermined data;
The storage device according to claim 1. when the predetermined data determined to be frequently used is not present in the first storage area, the data control means writes the predetermined data stored in the second storage area to the first storage area;
The storage device according to claim 2. an access control unit that accesses data in the first storage area or the second storage area in response to a request from a host device;
When a read error occurs when the access control means accesses specific data in the first storage area in response to a read request from a host device,
the data control means restores the specific data in the first storage area based on the additional information stored together with the specific data in the first storage area and the additional information stored together with the specific data in the second storage area;
The storage device according to claim 1 . The present invention is configured in a solid state drive (SSD) having the first memory and the second memory,
The storage device according to claim 1. A storage device having a first memory which is a non-volatile storage medium and a second memory which is a non-volatile storage medium having a processing speed slower than that of the first memory,
Calculating a usage frequency of data stored in a first storage area constructed in the first memory;
Based on the calculated frequency of use, the frequency of use of the data is determined,
writing the data determined to be used infrequently into a second storage area constructed in the second memory;
In the writing step, data stored in the first storage area and determined to be frequently used is periodically written to the second storage area;
The data is stored in the first storage area or the second storage area together with additional information;
The additional information includes a command number corresponding to a write request from a host device.
Storage control methods. A storage device having a first memory which is a non-volatile storage medium and a second memory which is a non-volatile storage medium having a processing speed slower than that of the first memory,
A process of calculating a frequency of use of data stored in a first storage area constructed in the first memory;
A process of determining whether the data is used frequently or not based on the calculated frequency of use;
A process of writing data determined to be used infrequently into a second storage area constructed in the second memory;
on the computer ,
In the writing process, data stored in the first storage area and determined to be frequently used is periodically written to the second storage area;
The data is stored in the first storage area or the second storage area together with additional information;
The additional information includes a command number corresponding to a write request from a host device.
program.

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