JPH04257018A - Storage system control system - Google Patents

Abstract

PURPOSE:To improve the throughput of a system by sharply improving a hit ratio for a file stored in a buffer storage device. CONSTITUTION:The entire file of one part of the file stored in a secondary storage device 20, and one part of the file of one part of the residual part, are respectively stored in a file entire area 31 and a file one part area 32 of a buffer storage device 30. Then, when an access to the desired file is performed of, whether or not the desired file is stored in the buffer storage device 30 is judged, and when the entire desired file is stored in the file entire area 31, the file is read out from the file entire area 31. Then, when one part of the desired file is stored in the file one part area 32, the file is read out from the file one part area 32, and the residual part of the desired file is read out from the secondary storage device 20. Then, when the desired file is not stored in the buffer storage device, the file is read out from the secondary storage device.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION The present invention provides overall control of a large-capacity, low-cost secondary storage device and a high-speed buffer storage device that stores copies of files stored in the secondary storage device.
The present invention relates to a storage system control method that effectively uses a high-speed buffer storage device for file access from an access request source.

0002

2. Description of the Related Art In current storage systems, large-capacity, low-cost storage devices (such as optical disks) have been put into practical use and are commercially available as one component of the storage system. The advantage of using a large-capacity, low-cost storage device is that a large-capacity storage system can be constructed at a low cost. However, the access speed and transfer speed are slower than magnetic disk devices, etc., and the system performance is lower than that of storage systems configured with magnetic disk devices. To avoid this, we provide a high-speed, small-capacity buffer storage device that holds copies of some files in the storage device, and if the requested file exists in the buffer storage device, we immediately transfer the file to the requester. A method (usually called a staging method or a caching method) is adopted. In the present invention, since the description is based on a staging method, a large-capacity, low-cost storage device will be referred to as a secondary storage device.

[0003] In the staging method, a method is usually adopted in which a copy of a part of the file in the secondary storage device is held in a buffer storage device. Buffer storage devices are generally expensive and have a small capacity, which limits their storage capacity and the number of files they can hold. therefore,
When a requested file is not present in buffer storage, a need arises to access secondary storage.

On the other hand, the capacity of one file has tended to increase in recent years. For example, in a document filing system, there is a demand for storing all documents, tables, drawings, etc. as image data in order to manage them in a unified manner. In such a system, one document may be up to 100 pages in A4 size. Even if the image data is compressed, one document will be nearly 10MB, and one file will have a capacity of 10MB. If such large-capacity files are held in a buffer storage device, the number of files that can be held will become smaller and smaller because the buffer storage device has a small capacity.

[0005]

[Problems to be Solved by the Invention] As mentioned above, in the conventional staging method, the buffer storage device can only hold a small number of files due to its small capacity, and there are many cases where the requested file does not exist in the buffer storage device. do. In such a case, it becomes necessary to access the secondary storage device, which has the disadvantage of reducing system throughput.

The present invention has been made in view of the above, and
The purpose is to provide a storage system control method that significantly improves the hit rate for files stored in a buffer storage device and improves system throughput.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the storage system control method of the present invention includes a large-capacity secondary storage means that stores all files, and a large-capacity secondary storage means that stores all files. buffer storage means for storing the whole of some of the files stored in the secondary storage means and a part of the remaining files stored in the secondary storage means, and accessing the desired files; a determination means for determining whether or not the desired file is stored in the buffer storage means; and a determination means for determining whether or not the desired file is stored in the buffer storage means; When it is determined that the desired file is stored, the entire desired file is read from the buffer storage means, and when it is determined that a part of the desired file is stored in the buffer storage means, the desired file is read out from the buffer storage means. reading a part of the file from the buffer storage means and reading the remaining part of the desired file from the secondary storage means, and when it is determined that the desired file is not stored in the buffer storage means; The gist of the present invention is to include readout control means for controlling reading of a desired file from the secondary storage means.

[0008]

[Operation] In the storage system control method of the present invention, the entirety of some of the files stored in the secondary storage means and a portion of the remaining files are stored in the buffer storage means, and the desired When access occurs to a file, it is determined whether or not the desired file is stored in the buffer storage means, and when the entire desired file is stored in the buffer storage means, the desired file is accessed. When the entire file is read from the buffer storage means and a part of the desired file is stored in the buffer storage means, the part of the desired file is read out from the buffer storage means and the remaining part of the desired file is stored as a secondary file. When the desired file is read from the storage means and is not stored in the buffer storage means, the desired file is controlled to be read from the secondary storage means.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a storage system control method according to an embodiment of the present invention. The storage system control method shown in the figure includes a secondary storage device 20 and a buffer storage device 30 connected to one or more control devices 10. The buffer storage device 30 is the entire file area 31
, the file is divided into partial areas 32. The whole file area 31 is an area where the entirety of one file is held for a plurality of files, and the partial file area 32 is an area where a part from the beginning of one file is held for a plurality of files. The reason for retaining a portion from the beginning of the file is as follows. After a file access request is made from the control device 10 to the secondary storage device 20, the file is transferred to the control device 10.
The time it takes for the control device 10 to start transferring the file from the beginning to the time it takes for the control device 10 to process a part of the file from the beginning with the file request source is made approximately equal. While a part of the file from the beginning is being processed, the following file is transferred from the secondary storage device 20, and one file is continuously processed without any time delay. In order to maintain this continuity, a part of the necessary file from the beginning is held in the file partial area 32. The storage capacity required for a portion from the beginning of the file is determined by taking into consideration the required performance and functions of the entire storage system, the performance and configuration of the secondary storage device 20, and the performance and capacity of the buffer storage device 30. .

The control device 10 and the secondary storage device 20 are connected by a connection line 40. The control device 10 and the buffer storage device 30 are connected by a connection line 50. Control device 10
is file table 11, buffer storage capacity table 1
It is equipped with 2.

FIG. 2 shows an example of the structure of each table. FIG. 2(a) shows the configuration of the file table 11. This file table 11 contains the file name of the file, a staging identification flag indicating whether or not the file exists in the buffer storage device 30, the total capacity of the file, and the file table 11 regarding all files held in the storage system. The capacity at which a part of the file from the beginning should be held in the partial file area 32, the latest access time to the file, and the number of times the file has been accessed are stored. The staging identification flag is set to 0, for example, when the buffer storage device 30 does not hold a copy of the file, and holds a copy of the entire file (
For example, 1
For example, 2 is used when a partial copy of the file from the beginning is held (held in the file partial area 32). For example, 3 is stored in the storage device 20 when it is not stored. In addition, although the relevant file is held in both the buffer storage device 30 and the secondary storage device 20,
When the files held in the entire file area 31 and partial file area 32 in the buffer storage device 30 are updated, for example, 4 and 5 are respectively stored in the staging identification flag. The number of accesses to the relevant file is calculated by counting the total number of times the file in the secondary storage device 20 and the file in the partial file area 32 are accessed, and a threshold α, which will be described later, is set. .

FIG. 2(b) shows buffer storage capacity table 1.
The configuration of No. 2 is shown below. The used capacity and unused capacity of the entire file area 31 and partial file area 32 are stored.
The used capacity is provided with thresholds β and γ, which will be described later.

FIG. 3 shows an example of the control flow when writing a new file. If a new file 61 needs to be written to the storage system (step 6
00), the control device 10 stores the buffer storage capacity table 12
, it is determined whether the used capacity of the entire file area 31 exceeds a certain threshold β (step 601). If it does not exceed β, the connection line 50
The entire file area 3 in the buffer storage device 30 through
A new file 61 is written in the unused area of No. 1, and the file table 11 and buffer storage capacity table 12 are updated (step 604). Hereinafter, the description of updating of tables will be omitted as it will be done as necessary, but if a particular explanation is required, it will be described.

If it exceeds β, the buffer storage capacity table 12 is referred to and it is determined whether the used capacity of the partial file area 32 exceeds a certain threshold γ (step 602). If it does not exceed γ, refer to the latest access time in the file table 11 and determine the known LRU (Least Recently Used)
The file 62 to be moved from the entire file area 31 to the partial file area 32 (referred to as destaging) is determined using an algorithm or the like, and a portion of the file 62 is written from the beginning to an unused area of the partial file area 32. The area of the file 62 in the entire file area 31 is set as an unused area, and the number of accesses regarding the file 62 in the file table 11 is set to 0 (step 603). Thereafter, the new file 61 is written into an unused area of the entire file area 31 (step 604).

If the value exceeds γ, the file 63 to be destaged from the partial file area 32 to the secondary storage device 20 is determined using an LRU algorithm, the area of the file 63 is made an unused area, and the file table 11 is The number of accesses regarding file 63 is updated by subtracting 1 (step 605). After that, the entire file area 31
From file 62 to the unused area of file partial area 32
A part is written from the beginning of the file 62, and the area of the file 62 in the entire file area 31 is made an unused area, and the number of accesses regarding the file 62 in the file table 11 is updated by subtracting 1 (step 603). Write a new file 61 in the unused area of the entire file area 31 (step 6
04).

FIG. 4 shows an example of a control flow when reading a file. When it becomes necessary to read file 71 from the storage system (step 700)
, the control device 10 refers to the file table 11 and determines whether the corresponding file 71 exists in the entire file area 31 (step 701). If the file 71 exists, read the file 71 from the entire file area 31,
Necessary processing is performed (step 702).

If the file 71 does not exist, the file table 11 is referred to and it is determined whether a portion from the beginning of the file 71 exists in the file partial area 32 (step 703). If a part from the beginning of the file 71 exists in the file partial area 32, the file partial area 32
The file 71 is read from (step 704). At the same time, a command is given to the secondary storage device 20 through the connection line 40 to read out the rest of the file 71 following the part of the file 71 stored in the partial file area 32 (step 705). The secondary storage device 20 reads the remaining portion of the file 71 from the corresponding medium and transfers it to the connection line 40.
The information is transferred to the control device 10 through the control device 10, and the control device 10 performs necessary processing (step 706).

Furthermore, the control device 10 updates the number of accesses regarding the file 71 in the file table 11 by adding 1, and determines whether the number of accesses exceeds a certain threshold α (step 707). If it does not exceed α, terminate. If it exceeds α, it is determined whether the used capacity of the entire file area 31 exceeds β (step 708). If the value does not exceed β, the entire file 71 is written to an unused area of the entire file area 31 (step 709). If it exceeds β, refer to the buffer storage capacity table 12 and
It is determined whether the used capacity of No. 2 exceeds γ (step 710). If it does not exceed γ, the file 72 to be destaged from the entire file area 31 to the file partial area 32 is determined using an LRU algorithm, and the file 72 is transferred to an unused area of the file partial area 32.
A part is written from the beginning of the file 72 in the file partial area 32 as an unused area, and the number of accesses regarding the file 72 in the file table 11 is updated by subtracting 1 (step 711). Thereafter, the file 71 is written to an unused area of the entire file area 31 (step 712).

If γ is exceeded in step 710, the partial file area 32 is removed using an LRU algorithm or the like.
Determine the file 73 to be destaged from to the secondary storage device 20, set the area of the file 73 as an unused area,
The number of accesses regarding the file 73 in the file table 11 is updated by subtracting 1 (step 713). Thereafter, the file 72 is written from the entire file area 31 to an unused area of the partial file area 32. The area of the file 72 in the entire file area 31 is set as an unused area, and the number of accesses regarding the file 72 in the file table 11 is increased by 1.
is updated by subtracting it (step 711). The file 71 is written in an unused area of the entire file area 31 (step 712).

In the check at step 703, if part of the file 71 does not exist in the partial file area 32, the secondary storage device 20 is instructed to read the file 71.
(step 714). The secondary storage device 20 reads the file 71 and transfers it to the control device 10, and the control device 10 performs necessary processing (step 715). Further, the control device 10 refers to the buffer storage capacity table 12 and determines whether the used capacity of the partial file area 32 exceeds γ (step 716). If it does not exceed γ, a portion of the beginning of the file 71 is written to an unused area of the partial file area 32 (step 717). If it exceeds γ, the file 73 to be destaged from the partial file area 32 to the secondary storage device 20 is determined using an LRU algorithm or the like. The area of file 73 is set as an unused area, and the number of accesses related to file 73 in the file table 11 is updated by subtracting 1 (step 7).
18). After that, a part of the beginning of the file 71 is written to an unused area of the file partial area 32 (step 717
).

FIG. 5 shows an example of the control flow when updating a file. When it becomes necessary to update the file 81 (step 800), the control device 10 refers to the file table 11 and determines whether the corresponding file 81 exists in the entire file area 31 (step 80).
1). If file 81 exists, the entire file area 3
1 file 81 is updated (step 802). If the file 81 does not exist, the file table 11 is referred to and it is determined whether a portion from the beginning of the file 81 exists in the file partial area 32 (step 803).

If the part from the beginning of the file 81 exists in the partial file area 32, the part from the beginning of the file 81 in the partial file area 32 is updated (step 80).
4). If it is necessary to update the remaining part of the file 81 following the part from the beginning of the file 81, the secondary storage device 20 is commanded to read the remaining part of the file 81 (step 805). Secondary storage device 20
reads the remaining part of the file 81 and sends it to the control device 10.
The control device 10 updates the remaining portion of the file 81 (step 806). Further, the control device 10 updates the number of accesses regarding the file 81 in the file table 11 by adding 1, and determines whether the number of accesses exceeds α (step 807). If it does not exceed α, terminate.

[0024] If it exceeds α, the entire file area 31
It is determined whether or not exceeds β (step 808). β
If it has not exceeded the limit, the entire file 81 is written to an unused area of the entire file area 31 (step 809).
). If it exceeds β, the file table 11 is referred to and it is determined whether the used area of the partial file area 32 exceeds γ (step 810). If it does not exceed γ, the file 82 to be destaged from the entire file area 31 to the partial file area 32 is determined using an LRU algorithm, etc. Write the part. The area of the file 82 in the file partial area 32 is set as an unused area, and the number of accesses regarding the file 82 in the file table 11 is updated by subtracting 1 (step 811). Thereafter, the file 81 is written to an unused area of the entire file area 31 (step 812). If γ is exceeded in the check at step 810, the file 83 to be destaged from the file partial area 32 to the secondary storage device 20 is determined using an LRU algorithm or the like. File 83
The area is set as an unused area, and the number of accesses related to file 83 in the file table 11 is updated by subtracting 1 (
step 813). After that, the file 82 is written from the entire file area 31 to the unused area of the partial file area 32, the area of the file 82 of the entire file area 31 is made an unused area, and the file 82 of the file table 11 is
The number of accesses related to the process is updated by subtracting 1 from the number of accesses (step 811). The file 81 is written in an unused area of the entire file area 31 (step 812).

If it is determined in step 803 that part of the file 81 does not exist in the partial file area 32, the secondary storage device 20 is commanded to read the file 81 (step 814). The secondary storage device 20 reads the file 81 and transfers it to the control device 10. The control device 10 updates the file 81 and updates the file table 11.
The number of accesses regarding file 81 is updated by adding 1 (step 815). Further, the control device 10 refers to the buffer storage capacity table 12 and determines whether the used capacity of the partial file area 32 does not exceed γ (step 816). If it does not exceed γ, file 8
1 is written into an unused area of the partial file area 32 (step 817). If it exceeds γ, LR
From file partial area 32 to 2 using U algorithm etc.
The file 83 to be destaged to the next storage device 20 is determined. The area of the file 83 is set as an unused area, and the number of accesses regarding the file 83 in the file table 11 is updated by subtracting 1 (step 818). Thereafter, a portion of the beginning of the file 81 is written into an unused area of the partial file area 32 (step 817).

[0026] Note that the new file 61 and the updated file 8
For writing to the secondary storage device 20 of No. 1, it may be determined whether to perform it in real time or off-line by referring to the staging identification flag of the file table 11 and taking into consideration the required performance of the system.

In this embodiment, the secondary storage device 20 has been described as a fixed media storage device, but it may also be an automatic media exchange type storage device (drive device, automatic media exchange device, etc.) that automatically exchanges removable media. (consisting of a media storage, etc.) will be easily understood by those skilled in the art from this embodiment. Furthermore, the table formats and control flow examples used in this embodiment are merely examples, and can be arbitrarily designed according to the specific implementation method of the present invention.

[0028]

[Effects of the Invention] As explained above, according to the present invention,
The entirety of some of the files stored in the secondary storage means and a portion of the remaining files are stored in the buffer storage means, and when a desired file is accessed, the corresponding determining whether a desired file is stored in the buffer storage means, and when the entire desired file is stored in the buffer storage means;
When the entire desired file is read from the buffer storage means and a part of the desired file is stored in the buffer storage means, the part of the desired file is read from the buffer storage means and the remaining part of the desired file is stored. 2
When the desired file is read from the secondary storage means and the desired file is not stored in the buffer storage means, the desired file is read from the secondary storage means, so compared to the conventional method, a large number of files can be stored. can be stored in the buffer storage means, and the hit rate for files stored in the buffer storage means can be dramatically increased;
Furthermore, when a part of the desired file is stored in the buffer storage means, the secondary storage means is accessed while the desired file is being read from the buffer storage means,
The remaining portion of the desired file can be read out from the secondary storage means without delay, and system performance can be prevented from deteriorating. In addition, since the files to be stored in the buffer storage means are determined by the number of accesses, for example, if the wrong file is accessed (usually only once), the wrong file is stored in the buffer storage means. Staging can be prevented and buffer storage means can be effectively utilized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a storage system control method according to an embodiment of the present invention.

FIG. 2 is a diagram showing the configuration of a file table and a buffer storage capacity table used in the storage system control method shown in FIG. 1;

FIG. 3 is a flowchart showing the operation of the storage system control method of FIG. 1 when writing a file;

4 is a flowchart showing the operation of the storage system control method of FIG. 1 when reading a file; FIG.

FIG. 5 is a flowchart showing the operation of the storage system control method of FIG. 1 when updating a file.

[Explanation of symbols]

10 Control device 11 File table 12 Buffer storage device table 30 Buffer storage device 31 Entire file area 32 File part area

Claims (2)

[Claims] [Claim 1] A large-capacity storage device that stores all files.
a second storage means, the whole of some of the files stored in the secondary storage means, and a part of the remaining files of the files stored in the secondary storage means; a buffer storage means for storing; a determination means for determining whether or not a desired file is stored in the buffer storage means when a desired file is accessed; and a determination result of the determination means. When it is determined that the entire desired file is stored in the buffer storage means, the entire desired file is read out from the buffer storage means, and a part of the desired file is stored in the buffer storage means. When it is determined that the desired file is stored in the buffer storage means, a part of the desired file is read out from the buffer storage means and the remaining part of the desired file is read out from the secondary storage means, and the desired file is stored in the buffer storage means. 1. A storage system control method, comprising read control means for controlling the desired file to be read from the secondary storage means when it is determined that the desired file is not stored in the storage means. 2. The storage system control method according to claim 1, further comprising means for determining the file to be stored in the buffer storage means based on the number of accesses to the file.