JPH06124239A - Resident data controller for cache memory - Google Patents

Abstract

PURPOSE:To effectively utilize a cache memory by automatically making data management information in a filing system resident on the cache memory corresponding to an access frequency. CONSTITUTION:In the case of the reading processing of data, when the read data are present in a magnetic disk 18 working as the cache memory, a controller 12 transfers the data read from the magnetic disk 18 to a host computer 10. On the other hand, when the read data are not present in the magnetic disk 18, the controller 12 reads the data from the optical disk 16 of an automatic changer 14 to be transferred to the host computer 10. In this case, when the access frequency of management information data managed by the controller 12 exceeds a certain fixed value, the controller 12 writes the data read from the optical disk 16 in the magnetic disk 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resident data control device for a cache memory, which controls a part of data management information in a file system so that the data can be accessed by being resident in the cache memory. The present invention relates to a resident data control device for a cache memory that automatically controls the cache memory so that the cache memory can be accessed and accessed according to the access frequency.

[0002]

2. Description of the Related Art A file system, in particular, a file system having a storage device that takes a long time to access, such as an optical disk autochanger, has a hard disk such as a magnetic disk as a cache memory.
When there is a request for writing general information, the contents are once put in the magnetic disk, and after a certain time, the contents are copied to the optical disk so that quick writing can be performed.

Data management information, such as data management information in a file system, which takes too long to access when placed on an optical disk, is fixed to a magnetic disk acting as a cache memory so that quick file management can be performed. I have to.

However, conventionally, all the data management information or a part of the data management information is always resident in the cache memory regardless of the access frequency.

[0005]

Therefore, when the system is changed to increase the size of the file system or when the number of file systems increases, the amount of data management information to be made resident in the cache memory also increases. However, there are problems such as increasing the size of the cache memory and limiting the resident data management information.

The present invention has been made to solve the above-mentioned conventional problems, and controls the data management information in the file system so that it automatically resides in the cache memory and is accessed according to the access frequency. It is an object of the present invention to provide a resident data control device of a cache memory, which is capable.

[0007]

SUMMARY OF THE INVENTION The present invention provides a resident data control device for a cache memory that controls a part of the data management information in a file system so that it can be made resident in the cache memory and accessed. A means for calculating and retaining the access frequency, a means for making data management information with high access frequency within a predetermined time resident in the cache memory, and a data management information with low access frequency for a predetermined time in the cache memory Means for canceling the resident state are provided to achieve the above object.

Further, the resident object is a super block in which information on the entire file system is stored, and an index list in which an index table is stored.

[0009]

In the present invention, the access frequency of the data management information is calculated and held, and the data management information having a high access frequency within a predetermined time is made resident in the cache memory,
On the other hand, the data management information having a low access frequency within the predetermined time is released from the resident state of the cache memory. Therefore, the data management information can be automatically made resident in the cache memory according to the access frequency.

In particular, the resident object is a super block containing information about the entire file system,
In addition, when the index list contains the index table, it can be efficiently made resident.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention applied to a UNIX system will be described in detail below with reference to the drawings.

The hardware for implementing the invention is
As shown in FIG. 1, a host computer 10, a controller 12 controlled by the host computer 10, an optical disc autochanger 14 controlled by the controller 12, and a cache memory for an optical disc 16 stored in the optical disc autochanger 14. And a magnetic disk 18 that operates.

The host computer 10 is a controller 1
By controlling 2, the optical disc 16 stored in the autochanger 14 can be accessed.

That is, in the writing process of the optical disk 16, first, the data is written on the magnetic disk 18 which functions as a cache memory. Of the data written to the magnetic disk 18, all general information is copied to the optical disk 16 after a fixed time. On the other hand, part of the management information data is made resident in the magnetic disk 18 according to the present invention.

In the data read process, if read data exists in the magnetic disk 18 acting as a cache memory, the controller 12 transfers the data read from the magnetic disk 18 to the host computer 10. On the other hand, when there is no read data on the magnetic disk 18, the controller 12 reads the data from the optical disk 16 of the autochanger 14, and the host computer 1
Transfer to 0. At this time, when the access frequency of the management information data managed by the controller 12 exceeds a certain value, the controller 12 writes the data read from the optical disk 16 to the magnetic disk 18 according to the present invention.

FIG. 2 shows the configuration of software for implementing the present invention. This software comprises an operating system (OS) 20, a driver 22 that controls the controller 12 according to the operating system 20, and a daemon 24 that controls the system.

The driver 22 can issue read and write commands to the controller 12.
Furthermore, the controller 12 also issues an instruction to make the data existing in the magnetic disk 18 acting as a cache memory resident, an instruction to release the resident data, and an instruction to acquire the data access frequency according to the present invention. be able to.

The daemon 24 uses the driver 22 at regular intervals to monitor the frequency of the data management information accessed by the controller 12, thereby resident processing of the data management information or canceling the resident processing. Perform processing.

In this embodiment, in the UNIX file system, a super block in which information about the entire disk system such as the size of the disk, the boundary value of the area, the head pointer of the unused block list, etc. is stored, and each file and The index (i-) list, which contains directory management information and pointers to actual file areas, is made resident.

The operation of this embodiment will be described in detail below with reference to FIG.

At step 100, a resident management information database created by monitoring the access frequency of the data management information is read into the memory of the daemon 24. Next, at step 102, the data management information number i to be made resident is initialized to 1.

Next, at step 104, the i-th access frequency of the resident management information database is read. Next, at step 106, the access frequency within a predetermined time is calculated by subtracting the previous access frequency from the current access frequency.

Then, the process proceeds to step 108 and step 1
It is determined whether or not the access frequency calculated in 06 is a resident target having a predetermined value or more. If the determination result is true, the process proceeds to step 110, and it is determined from the information in the resident management information database whether or not the magnetic disk 18 has already been made resident. If the determination result is false, the process proceeds to step 112, and the i-th block is made resident in the magnetic disk 18, and the data indicating the resident state is set to 1.

On the other hand, when the result of the determination in step 108 is false and it is determined that the object is not made resident,
Proceeding to step 120, it is determined whether the access frequency calculated in step 106 is the target of resident cancellation that has become a predetermined value or less. If the determination result is true, the process proceeds to step 122 and it is determined whether or not the device is made resident. When the determination result of step 122 is true, the routine proceeds to step 124, the resident block of the i-th block is released, and the data indicating the resident state is set to 0.

On the other hand, when the determination result of the above-mentioned step 110 is true and the target is made resident but already made resident, the determination result of the above-mentioned step 120 is false and the resident and resident release are made. When it is not any of the above, the determination result of the above-mentioned step 122 is false, and it is the target of the resident release but is not made resident, or when step 112 or 124 is completed, the process proceeds to step 130, The current access frequency calculated in step 106 is changed to the previous access frequency, and the data management information number
Increment i by 1.

Next, in step 132, it is determined whether the incremented data information number i is less than or equal to its maximum value N. If the determination result is false, the process returns to step 104. On the other hand, when the result of the determination in step 132 is true, the process this time is ended.

FIG. 5 shows an example of the relationship between the elapsed time, access frequency, and resident / unresident status in this embodiment.

In this embodiment, since the super block and the i-list are made resident in the UNIX file system, the resident can be made efficient. That is, the UNIX file creation sequence is as shown in FIG. 6, for example, and when creating a UNIX file, a super block, which is one of data management information, is frequently used. Also, an i-node for managing the information of the UNIX file that also constitutes the i-list
Is also used frequently. Therefore, of the i-list, which is a unit of super blocks and i-nodes,
By making the frequently accessed objects resident in the cache memory, efficient file control can be performed.

Also in the UNIX file access sequence, as shown in FIG. 7, i-nodes are frequently used, and it can be seen that the effect of making the i-list resident is high. In addition, in FIG. 7, the path name is a descriptive name for specifying the UNIX file.

On the other hand, compared to the super block and i-list, the directory is used less frequently and is not required to be accessed at high speed. Therefore, the same data area as general information can be dealt with and the directory is always made resident. No need. Of course, if the cache memory has enough space, the directory can be made resident.

In the above embodiment, the present invention is
Although it has been applied to the file system of the UNIX system including the optical disc autochanger, the application target of the present invention is not limited to this.

The type of cache memory is not limited to the magnetic disk.

[0033]

As described above, according to the present invention, since the data management information in the file system is automatically resident in the cache memory according to the access frequency, the cache memory can be effectively used. Even if the system is changed to increase the size of the file system or the number of file systems is increased, the fixed size cache memory can be effectively used. Further, by making data management information indicating the location of a file resident, such as the i-list of the UNIX system, the access to a file in a frequently used file system can be speeded up. Have the effect.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of hardware in which the present invention is implemented.

[Fig. 2] Similarly, a diagram showing the configuration of software

FIG. 3 is a flowchart showing a processing procedure of an embodiment of the present invention.

FIG. 4 is a diagram showing an example of a resident management information database used in the embodiment.

FIG. 5 is a diagram showing an example of a relationship between an access frequency and a resident state and a resident release state in the embodiment.

FIG. 6 is a flow chart showing a creation sequence of a UNIX file showing a usage state of a super block and an i-list which are made resident in the embodiment.

FIG. 7 is a flowchart showing an example of a UNIX file access sequence.

[Explanation of symbols]

 10 ... Host computer 12 ... Controller 14 ... Optical disk autochanger 16 ... Optical disk 18 ... Magnetic disk 20 ... Operating system (OS) 22 ... Driver 24 ... Daemon

Claims (2)

[Claims] 1. A resident data control device of a cache memory, which controls a part of data management information in a file system so that the data can be accessed by being resident in the cache memory, and calculates and holds the access frequency of the data management information. Means, means for making data management information with high access frequency within a predetermined time resident on the cache memory, and means for releasing data management information with low access frequency within a predetermined time from the resident state of the cache memory, A resident data control device for a cache memory, comprising: 2. The resident object according to claim 1,
A resident data control device for a cache memory, which is a super block that stores information about the entire file system and an index list that stores an index table.