JP2002108704A - Disk cache control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that there is no effect of caching when a proper disk cache mode matching the access mode of a file is not set. SOLUTION: A system which effectively uses a disk cache is provided and a disk cache control means 81 sets a plurality of disk cache modes for a magnetic disk processor 4. A file area securing means 82 secures a file in an area on a disk where a mode suitable for the file is set in the cache modes set by the disk cache control means 81. A file allocation means 83 sets an optimum cache mode by the disk cache control means 81 according to the file access type when the file is used. Thus, the optimum cache mode is set in correspondence with the file using the cache mode and the cache can be effectively used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a system for controlling a disk cache, and more particularly to setting a plurality of cache modes for one disk device and selecting a cache mode suitable for a file access mode of an application of a higher-level device. And a disk cache control system for processing.

[0002]

2. Description of the Related Art Various attempts have been made in the past to shorten the access time in accessing the magnetic disk device 6. Factors that affect the access time of the magnetic disk device 6 include a seek process for positioning the magnetic head in the recording area to be accessed, a rotation waiting process for the positioned recording area, and a data hit ratio in the disk cache mechanism.

[0003] Disk cache mechanisms include RAM and EE.
When a semiconductor memory such as a PROM is used and the information of the main storage memory is written between the magnetic disk device and the main storage memory to the magnetic disk device, and when the information of the magnetic disk device is read to the main storage memory, Is temporarily stored. As a result, if there is information to be accessed in the disk cache before accessing the magnetic disk device, the information is transferred to and from the main storage memory, thereby reducing the actual number of accesses to the magnetic disk device and improving performance. It is intended to improve.

As a cache mode of a disk cache system in a conventional magnetic disk device, for example, a write-through system or a write-back system can be cited. The cache mode is set to one mode for one device. The cache mode was specified when I / O was issued.

[0005]

However, this prior art has the following problems.

A first problem is that even if a cache mode is designated for a device, an appropriate cache mode is not designated when executing input / output to / from a file on a magnetic disk device. The effect of the cache cannot be obtained sufficiently. The reason is that there is an appropriate cache mode depending on the access mode of the file from the program, and if the appropriate mode is not set or specified, the effect of the cache is lost.

[0007]

A first disk cache control system according to the present invention comprises: a magnetic disk drive; a magnetic disk cache having a memory for speeding up input / output processing with the magnetic disk drive; In a disk cache control system comprising: a magnetic disk processing device that controls a magnetic disk device and the magnetic disk cache; and a CPU that controls the magnetic disk processing device from a main device, the magnetic disk cache is provided in the main device. The cache mode, which is the operation mode, and the cache memory size allocated to the cache mode are set in the magnetic disk cache, and the cache mode and the start address and end address of the magnetic disk device to which the cache mode is applied are determined by the magnetic disk processing. A disk cache control unit for setting area information as an area information, and determining and assigning an address of the area to a file for which a new area is to be secured in the magnetic disk device based on an access mode of the file based on an access mode of the file. And a cache mode that matches the access mode of the file when the file is opened, and checks whether the file is included in the area information having the cache mode. File allocation means for creating area information from the cache mode and the location information of the file and registering the area information in the magnetic disk processing device.

A second disk cache control system according to the present invention includes allocating a cache mode to which the area of the magnetic disk device is applied.

A third disk cache control system according to the present invention includes that a cache mode suitable for the access mode is operated from a file access mode.

In a fourth aspect of the present invention, in the first or second aspect, the area information comprises a cache mode and a start address and an end address of a magnetic disk device to which the cache mode is applied. It is prepared.

A fifth disk cache control system according to the first or second aspect of the present invention, wherein the cache mode described in the area information including the input / output address of the magnetic disk device operates at the time of input / output. Prepare to do.

A sixth disk cache control system according to the present invention, in the second invention, comprises determining a cache memory size of the cache mode according to an area amount of the magnetic disk device allocated to the cache mode.

In a seventh aspect of the present invention, in the disk cache control system according to the third aspect, the access mode includes a data copy mode applied when copying data and a data reuse mode used when broadcasting data. Prepare.

An eighth disk cache control system of the present invention according to the first, second or third invention is provided with that one or more cache modes operate simultaneously.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a first embodiment of the present invention will be described in detail with reference to the drawings.

Referring to FIG. 1, the configuration of an embodiment of a cache control system according to the present invention is based on a command from a CPU 7 of a main unit such as a personal computer, a workstation or a general-purpose computer. The magnetic disk cache 5 and the magnetic disk device 6 are controlled through the magnetic disk processing device 4. A command issued from the CPU 7 based on a request for setting the cache mode or the like from the application program 9 is received by the magnetic disk processing device 4 and has a configuration in which the magnetic disk cache 5 and the magnetic disk device 6 can be controlled. Shall be.

The magnetic disk cache 5 is composed of a semiconductor memory or the like, and is a memory for increasing the speed of input / output between the magnetic disk device 6 and the CPU 7. The magnetic disk processing device 4 supports a cache mode. And a program corresponding to the designated cache mode operates to control the cache memory of the magnetic disk cache 5.

The CPU 7 has an operating system 8
And an application program 9. The operating system 8 includes a file area management unit 80, a disk cache control unit 81, and a file area securing unit 82
And file allocation means 83.

Each of these means operates as follows.

The disk cache control means 81 determines the initial value, minimum value, and maximum value of the cache area size for each cache mode of the magnetic disk cache 5 for each magnetic disk device 6 for the magnetic disk processing device 4. The setting and the setting of the area start address and the area end address of the magnetic disk device 6 to which each cache mode is applied are performed. As for the set cache mode, cache size, area start address and area end address, the set value and the value during execution can be confirmed.

The file area securing means 82 secures a new file area on the magnetic disk device 6, sets an optimal cache mode for the secured area, and changes the cache size.

The file allocation means 83 confirms an access mode of a file used when the application program 9 operates, sets a cache mode optimal for the access mode, and changes a cache size.
In general, the access mode for a file is sequential access in which data is written or read sequentially from the beginning or middle of the file, direct access in which the record is accessed directly by specifying the number of the record to be accessed in the file, and index access in which the index is accessed. There is access. The access mode in the present invention is defined as an access mode that includes the data input mode and the output mode in addition to the above.

The file area management means 80 secures and releases a file area on the magnetic disk device 6, manages a free area, and the like.

The application program 9 is stored in the magnetic disk device 6
An application program that secures a file area above and writes or reads data in a certain access mode with respect to the secured file, and performs initial settings of a cache mode for the magnetic disk device 6 by a person in charge of the system. It shall include programs.

Next, the operation of one embodiment of the present invention will be described with reference to FIG. 1 and the flowcharts of FIGS.

First, the application program 9 is transmitted to the disk cache control unit 8 through the operating system 8.
In step 1, an initial value, a minimum value, and a maximum value are set for the magnetic disk processing device 4 as a cache mode applied to the magnetic desk cache 5 and a cache area size for each cache mode. Here, the initial value is the size of the disk cache 5 allocated to each cache mode immediately after system startup, and the minimum value is that the disk cache area used in another cache mode maintains the performance during operation. When there is a shortage, when the cache area of the own cache mode is given to another cache mode and the cache size of the own cache mode is reduced, the lower limit cannot be reduced any more, and the maximum value is the minimum value On the contrary, this is the upper limit value when the area held by the own cache mode is expanded.

In the disk cache control means 81, one or a plurality of cache modes can be set for one magnetic disk device 6, and the area of the magnetic disk device 6 to which each cache mode is applied is defined as a start address and an end address. One or more can be set.

The disk cache mode includes, for example, (1) STD mode, (2) TMP mode, and (3) SEQ mode.

In the (1) STD mode, with respect to write I / O from the host device, when a hit occurs in the magnetic disk cache 5, data is written in both the disk cache 5 and the magnetic disk device 6, and when a miss occurs, Only written on the magnetic disk device 6. Regarding read I / O, data is transferred from the disk cache 5 when a cache hit occurs, and data transfer and loading to the disk cache 5 are performed when a miss hit occurs.

In the TMP mode (2), the write I / O
Is written to both the disk cache 5 and the magnetic disk device 6 irrespective of the hit or mishit of the disk cache 5. For read I / O,
At the time of a cache hit, data is transferred from the disk cache 5, and at the time of a mishit, data is transferred from the magnetic disk device 6 and loading to the disk cache 5 is performed.

In the SEQ mode (3), the write I / O
With regard to (3), when a cache hit occurs, the information of the hit disk cache 5 is flushed (discarded) and written to the magnetic disk device 6 only. Even at the time of a mishit, writing is performed only in the magnetic disk device 6. As for the read I / O, data is transferred from the disk cache 5 when a cache hit occurs. At the time of a mishit, the read-ahead is performed from the magnetic disk device 6 exceeding the I / O request size and the data is loaded into the disk cache 5.

For example, when the access mode to a file from a program is sequential reading, the SEQ mode (3) is effective. This is because the data placed on the magnetic disk cache 5 can be fetched in advance without accessing the magnetic disk device 6. When data is copied, sequential reading and sequential writing are performed alternately. In this case, it is effective to prepare a cache mode in which the write side also holds several blocks of write data on the magnetic disk cache 5 and writes the data at a time in a certain state. At this time, assuming that the copy processing is executed between disks, the application program 9 associates the input-side file access mode with the (3) SEQ cache mode in the sequential input mode, and outputs the file-side access mode. Can be realized by associating the above-described cache mode in which several blocks of write data are held before writing with sequential access as the access mode designation. Even if a failure occurs at the time of output and the data remaining in the magnetic disk cache 5 is not written, it can be re-executed in the case of copy processing. In the case where the same data is broadcast to a plurality of locations, the read data is used many times. Therefore, a cache mode in which the data once read is kept on the magnetic disk cache 5 is defined. The program associates with the cache mode by designating the retention of read data as an access mode by sequential reading. As described above, it is possible to prepare a cache mode suitable for copy processing and broadcast transmission processing in addition to the cache modes other than the above (1) to (3). In the access mode according to the present invention, various modes such as an access mode corresponding to copy processing and a reuse mode for input data at the time of broadcast transmission can be designated from the application program 9 as an access mode. I have.

As described above, the disk cache control means 81, the file area securing means 82 and the file allocation means 83 determine the cache mode to be applied from the access mode of the file used by each application program 9. Next, the area of the magnetic disk device 6 is allocated to each cache mode. This allocation information is set on the magnetic disk processing device 4 and managed as area information including a cache mode, an area start address, and an area end address.

In executing the actual input / output, the area information is referred to by the address of the magnetic disk device 6 to be input / output, and a cache mode including the relevant address between the area start address and the area end address is used. The operation is performed by the magnetic disk processing device 4. still,
Regarding the input / output operation to the area of the magnetic disk 6 to which the cache mode is not assigned, the control is performed so that none of the cache modes operates. Also, when the application program 9 closes a file, the start and end addresses of the file area are notified to the corresponding cache mode, and the cache data for the file is deleted from the magnetic disk cache 5.

Next, a detailed description will be given with reference to the flowcharts of FIGS.

FIG. 2 shows the disk cache control means 81.
5 is a flowchart for explaining a process of initially setting a cache mode in FIG. This process is normally performed in conjunction with the initialization process of the magnetic disk device 6.

First, the application program 9 determines the cache mode to be applied to the target magnetic disk device 6 and the cache size (initial value, minimum value) to be secured in the magnetic disk cache 5 when operating in the cache mode. , The maximum value) and the area start address and the area end address of the magnetic disk device 6 to which the cache mode is applied, and requests the operating system 8 to perform processing (processing A1).

Upon receiving the request, the operating system 8 passes control to the disk cache control means 81. In the disk cache control means 81, for example, 2
One cache mode is designated, and the range from 0 giga (area start address) to (15 giga-1 byte) (area end address) of the magnetic disk device 6 having a capacity of 30 gigabytes is 15 gigabytes in the first cache mode. The range from giga (area start address) to (30 giga-1 byte) (area end address) can be set to be used in the second cache mode. In the above example, all the areas of the magnetic disk 6 are allocated to the respective cache modes, but there may be a part where the allocation is not performed.

The initial value of the cache mode on the magnetic disk cache 5 may be determined in conjunction with the area of the magnetic disk device 6 allocated to the cache mode. If there is no designation of the cache size related to the cache mode from the application program 9 for setting the cache information, the disk cache control means 81 sets the magnetic capacity in proportion to the area amount of each cache mode set on the magnetic disk device 6. The cache size on the disk cache 5 is determined. At this time,
The maximum value and the minimum value may be determined, for example, by adding or subtracting 50% of the initial value from the initial value.

As described above, all the cache modes to be applied are defined. After completing the definition, the disk cache control unit 81 issues a cache setting command in the new setting mode to the magnetic disk processing device 4 using the specified definition data as a parameter (process A2). As a result, the previously set information of the disk cache 5 is deleted, and a new cache mode and cache size are set. Similarly, a cache mode and a region start address and a region end address corresponding to the cache mode are newly set in the magnetic disk processing device 4 as area information. The magnetic disk processing device 4 uses the area information set in this way to determine which cache mode operates. It is also possible to set a plurality of discontinuous area information in the same cache mode.

At this time, a cache mode program corresponding to the cache mode can be set from the CPU 7 to the magnetic disk processing device.

FIG. 3 shows the disk cache control means 81.
9 is a flowchart for explaining cache setting information check processing in FIG. First, the application program 9 specifies a cache mode and an area size of a file to be created using the cache mode (process B).
1) and pass it to the operating system 8. Upon receiving this request, the operating system 8 transfers control to the disk cache control means 81. The disk cache control means 81 checks whether this request is satisfied. Disk cache control means 81
Obtains the area information based on the area start address and the area end address of the cache mode set in the magnetic disk processing device 4 (process B2), and determines whether there is a disk free area in the area that satisfies the request. Is checked by inquiring of the file area management means 80 (process B3). If there is an area that satisfies the condition, the area address of a free area that is included between the area start address and the area end address corresponding to the cache mode specified as the request source and satisfies the size requested to be secured is returned ( Process B4). If no area satisfies the condition, an error status is returned to the request source (process B5). If there is an area that satisfies the condition, the application program 9 of the request source
Then, the file area can be secured from the area address of the free area notified by the file area securing means 82.

FIG. 4 is a flowchart for explaining the flow of processing in the file area securing means 82. First, the application program 9 specifies an access mode and an area size of a file to be secured (process C1). Next, the operating system 8 that has received this designation passes it to the file area securing means 82. The file area securing unit 82 determines the disk cache mode from the access mode of the specified file, and activates the disk cache control unit 81 using the determined disk cache mode as an argument (process C2).

The disk cache control means 81 checks whether the disk cache mode passed as an argument has been defined on the magnetic disk processing device 4.

If the disk cache mode has been defined, the area information is obtained, and a request for securing an area satisfying the specified area size in the area is issued to the file area management means 80. Check the return status from the file area management means 80 (processing C
3) At the time of normal termination, the notified area is secured as a file (process C4). If there is no free space in the area in the check of (Process C3) and if the disk cache mode is not defined, a free space of any disk is requested from the file area management means 80 and secured ( (Process C5) Then, the disk cache control means 81 is started (process C6). The disk cache control unit 81 newly sets the area start address and area end address of the secured area and the cache mode for the area in the magnetic disk processing device 4.

FIG. 5 shows a file allocation means 83.
4 is a flowchart illustrating the flow of the process in FIG. First, the file allocating means 3 is called from a file open process of the operating system 8 based on a file open request of the application program 9. The file allocation means 83 obtains the access mode of the file and the file name of the file from the file open processing (processing D1). The file area management unit 80 is called based on the file name, and the start and end addresses of the area of the file are obtained. A cache mode suitable for the access mode is determined from the access mode, and the determined cache mode is set on the magnetic disk processing device 4 and the start and end addresses of the area of the file are included in the area of the cache mode. Is checked (process D2). If the cache mode is set and the file is included in the area of the cache mode, the process ends normally. (Process D
If the cache mode corresponding to the access mode is not set in the check in 2), or if the cache mode is set but is not included in the area, the file allocating means 3 determines the cache mode to be newly set and the corresponding cache mode. The disk cache control unit 81 is called using the area information of the start and end addresses of the file as arguments. The disk cache control unit 81 sets new area information on the magnetic disk processing device 4 based on the received information (process D3). As a result, the area information of the new cache mode is set for the file area of the file to be opened and the cache mode being applied is set to another area.

It should be noted that (Process C6) in FIG. 4 and (Process D) in FIG.
In 3), the disk cache control unit 81 extracts all the area information after the change from the magnetic disk processing device 4 in accordance with the setting of a new cache mode for the magnetic disk device 6 and the setting of the cache mode for another area. The sizes of the areas are totaled for each cache mode, and the cache size of the magnetic disk cache 5 is corrected based on the result, for example, in a proportionate manner. For example, when two cache modes are applied and the area amount of the magnetic disk 6 in the first cache mode is 20
When the amount of the second area is 10 mega, the magnetic disk cache 5 allocated to the first and second cache modes
, Etc., so that the distribution of the cache size is 2: 1.

FIG. 6 is a flowchart for explaining the flow of the disk cache control process at the time of accessing the disk after the file open process in the magnetic disk processing device 4 has been completed. It is checked whether there is a free space in the cache of the cache mode that matches the request access mode (process E1). If there is free space, the process is performed using the free space cache (process E3). If there is no free space, it is checked whether the cache size can be expanded (process E2). If expansion is not possible, old caches with old access in the request access mode cache are discarded and reused (process E4). If the size can be expanded, it is checked whether there is a free space in the cache in another cache mode (process E5). If there is a vacancy, the cache of the request cache mode is expanded by using the cache of another cache mode (processing E6). If there is no free space in the cache of another cache mode, the mode of the cache with the oldest access is checked (processing E
7). If it is the same as the request cache mode, the old cache is discarded and reused (process E8). If the cache in the other cache mode is old, the old cache in the other cache mode is discarded, reused in the request cache mode, and the cache size in the request cache mode is increased (process E9).

[0049]

The first effect is that the effect of the disk cache can be made effective. The reason is that an optimum cache mode can be set for a processing method for a file to be accessed, and a cache mode suitable for a file access mode in an application program is automatically set by the system.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart illustrating the operation of the embodiment of the present invention.

FIG. 3 is a flowchart illustrating the operation of the embodiment of the present invention.

FIG. 4 is a flowchart illustrating the operation of the embodiment of the present invention.

FIG. 5 is a flowchart illustrating the operation of the embodiment of the present invention.

FIG. 6 is a flowchart illustrating the operation of the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 4 magnetic disk processing device 5 magnetic disk cache 6 magnetic disk device 7 CPU 8 operating system 80 file area management means 81 disk cache control means 82 file area securing means 83 file allocation means 9 application program

Claims (8)

[Claims] 1. A magnetic disk device, a magnetic disk cache having a memory for speeding up input / output processing with the magnetic disk device, and a magnetic disk processing device for controlling the magnetic disk device and the magnetic disk cache And a CPU for controlling the magnetic disk processing device from a main unit, a cache mode which is an operation mode of the magnetic disk cache in the main unit and a cache memory size allocated to the cache mode. Disk cache control means for setting the cache mode and the cache mode and a start address and an end address of the magnetic disk device to which the cache mode is applied as area information in the magnetic disk processing device; File area securing means for allocating an address of the area for a file for which a new area is to be secured in the magnetic disk device based on an access mode of the file and determining a cache mode suitable for the address;
When a file is opened, a cache mode that matches the access mode of the file is selected, and it is checked whether the file is included in the area information having the cache mode. A file allocation means for creating the area information from the position information and registering the area information in the magnetic disk processing device. 2. The disk cache control system according to claim 1, wherein the area is allocated to a cache mode to which the area of the magnetic disk device is applied. 3. A disk cache control system wherein a cache mode suitable for the access mode is operated from a file access mode. 4. The disk cache control system according to claim 1, wherein the area information includes a cache mode and a start address and an end address of the magnetic disk device assigned to the cache mode. 5. The disk cache control system according to claim 1, wherein a cache mode described in the area information including an input / output address of the magnetic disk device operates when executing input / output. 6. The disk cache control system according to claim 2, wherein a cache memory size of the cache mode is determined according to an area amount of the magnetic disk device allocated to the cache mode. 7. The disk cache control system according to claim 3, wherein said access modes include a data copy mode applied when copying data and a data reuse mode used when broadcasting data. 8. The disk cache control system according to claim 1, wherein one or more cache modes operate simultaneously.