JP2773986B2 - Storage system control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention controls a large-capacity and low-cost secondary storage device and a high-speed buffer storage device for storing a copy of a file 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 a file access from an access request source.

[0002]

2. Description of the Related Art In a current storage system, a large-capacity low-priced storage device (such as an optical disk) has been put to practical use and is commercially available as one component of the storage system. Use of a large-capacity low-priced storage device has an advantage that a large-capacity storage system can be configured at low cost. However, the access speed and the transfer speed are lower than that of a magnetic disk device or the like, and the performance of the system is lower than that of a storage system constituted by magnetic disk devices. To avoid this, a high-speed and small-capacity buffer storage device that holds a copy of a part of the file in the storage device is provided, and if the requested file exists in the buffer storage device, the file is immediately transferred to the request source. A method (usually called a staging method or a caching method) is employed. In the present invention, a large-capacity low-priced storage device will be referred to as a secondary storage device in order to explain based on the staging method.

[0003] In the staging system, a method is generally employed in which a copy of a part of a file in a secondary storage device is held in a buffer storage device. Since the buffer storage device is generally expensive and has a small capacity, the storage capacity is limited, and the number of files to be stored is also limited. Therefore, when the requested file does not exist in the buffer storage device, it is necessary to access the secondary storage device.

On the other hand, the capacity of one file has been increasing in recent years. For example, in a document filing system, there is a demand that all documents, tables, drawings, and the like be stored as image data in order to manage them in a unified manner. In such a system, one document may cover 100 pages in A4 size. Even if image data is compressed, the size of one document is close to 10 MB, and the capacity of one file is 10 MB. When such a large-capacity file is stored in the buffer storage device, the buffer storage device has a small capacity, so that the number of files that can be stored is further reduced.

[0005]

As described above, in the conventional staging method, the buffer storage device has a small capacity, so that the number of files that can be held is small, and the requested file often does not exist in the buffer storage device. I do.
In such a case, it is necessary to access the secondary storage device, and there is a disadvantage that the system throughput is reduced.

[0006] The present invention has been made in view of the above,
It is an object of the present invention to provide a storage system control method in which a hit rate for a file stored in a buffer storage device is significantly improved, and a system throughput is improved.

[0007]

In order to achieve the above object, a storage system control method according to the present invention comprises: a large-capacity secondary storage means for storing all files; High-speed buffer storage means for storing the entirety of some of the files and the remaining part of the files stored in the secondary storage means; A determination unit that determines whether the desired file is stored in the buffer storage unit when an access occurs, and the entirety of the desired file is stored in the buffer storage based on the determination result of the determination unit. When it is determined that the desired file is stored in the buffer storage unit, the entirety of the desired file is read out from the buffer storage unit, and a part of the desired file is stored in the buffer storage unit. When it is determined that the file has been read, a part of the desired file is read from the buffer storage means, and a remaining part of the desired file is read from the secondary storage means, and the desired file is stored in the buffer storage means. When it is determined that the file is not stored, a read control unit that controls to read the desired file from the secondary storage unit and a file to be stored in the buffer storage unit are determined based on the number of times of access to the file. It is a gist of the present invention to have a determining means for performing the determination.

[0008]

According to the storage system control method of the present invention, it is possible to perform high-speed processing on all of the files and some of the remaining files among the files stored in the large-capacity secondary storage means. When the desired file is accessed in the buffer storage means, it is determined whether or not the desired file is stored in the buffer storage means, and the entire desired file is stored in the buffer storage means. When stored, the entirety of the desired file is read from the buffer storage means. When a part of the desired file is stored in the buffer storage means, a part of the desired file is read from the buffer storage means and the desired file is read. The remaining part of the file is read from the secondary storage means, and when the desired file is not stored in the buffer storage means, the desired file is And it is controlled so as to read from 憶 means. When storing a file in the buffer storage unit, the determination unit determines a file to be stored in the buffer storage unit based on the number of accesses to the file.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a storage system control system according to an embodiment of the present invention. The storage system control method shown in FIG. 1 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 stores the entire file area 3
1. It is divided into a file partial area 32. The whole file area 31 is an area for holding a plurality of files of one entire file, and the file partial area 32 is an area for holding a plurality of files from the beginning of one file. The reason for keeping a part 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
The time until the transfer is started to 0 and the time when the control device 10 processes a part of the file from the head of the file with the file request source are set to be substantially equal. While processing a part of the file from the beginning, the subsequent file is transferred from the secondary storage device 20, and one file is continuously processed without a time delay. In order to maintain this continuity, a part of the required file from the beginning is held in the file partial area 32. The storage capacity required for a part of the file from the beginning is determined in consideration of the required performance and functions of the entire storage system, the performance and configuration of the secondary storage device 20, the performance and capacity of the buffer storage device 30, and the like. .

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 the file table 11, the buffer storage capacity table 1
2 is provided.

FIG. 2 shows a configuration example of each table. FIG. 2A shows the configuration of the file table 11. This file table 11 contains the file names of the files for all the files held in the storage system.
A staging identification flag indicating whether or not the file exists in the buffer storage device 30; the capacity of the entire file; the capacity when a part from the beginning of the file is to be held in the file partial area 32; The latest access time to the file and the number of times to access the file are stored. In the staging identification flag, for example, 0 when the buffer storage device 30 does not hold a copy of the file, and 1 when the buffer storage device 30 holds a copy of the entire file (in the entire file area 31). Is stored in the buffer storage device 30 when a copy of the file from the beginning of the file is held (held in the file partial area 32), for example. When not stored in the storage device 20, for example, 3 is stored. The corresponding file is stored in both the buffer storage device 30 and the secondary storage device 20, but the entire file area 31 in the buffer storage device 30,
When the file held in the file partial area 32 is updated, for example, 4 and 5, respectively, are stored in the staging identification flag. The number of accesses to the file is 2
File in the secondary storage device 20 and file partial area 3
2 is a counter for counting the total number of times of accessing the file in 2, and a threshold α described later is provided.

FIG. 2B shows a buffer storage capacity table 1.
2 is shown. The used capacity and the unused capacity of the entire file area 31 and the partial file area 32 are stored.
The used capacity is provided with thresholds β and γ, respectively, which will be described later.

FIG. 3 shows an example of a control flow when a file is newly written. When it is necessary to write the new file 61 into the storage system (step 6)
00), the control device 10
, It is determined whether or not the used capacity of the entire file area 31 exceeds a certain threshold β (step 601). If it does not exceed β, connect line 50
File area 3 in buffer storage device 30 through
The new file 61 is written in the unused area of No. 1 and the file table 11 and the buffer storage capacity table 12 are updated (step 604). Hereinafter, updating of the tables and the like will be performed as needed, and the description will be omitted. However, if description is particularly necessary, the description will be made.

If it exceeds β, it is determined whether or not the used capacity of the file partial area 32 exceeds a certain threshold γ by referring to the buffer storage capacity table 12 (step 602). If it does not exceed γ, the latest access time of the file table 11 is referred to, and the entire file area 31 is moved to the file partial area 32 by using a known LRU (Least Recently Used) algorithm or the like (referred to as destaging). The file 62 is determined, and the file 62 is stored in an unused area of the file partial area 32.
Is written from the beginning, the area of the file 62 of the entire file area 31 is set as an unused area, and the number of accesses to the file 62 of the file table 11 is set to 0 (step 603). Thereafter, the new file 61 is written to an unused area of the entire file area 31 (step 6).
04).

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 the LRU algorithm or the like, the area of the file 63 is set as an unused area, and the file table 11 is used. The number of times of access to the file 63 is updated by subtracting 1 (step 605). Then, the entire file area 31
From the file 62 to the unused area of the file partial area 32
Is written from the beginning, the area of the file 62 in the entire file area 31 is set as an unused area, and the number of accesses to the file 62 in the file table 11 is updated by subtracting 1 (step 603). The new file 61 is written in the unused area of the entire file area 31 (step 6).
04).

FIG. 4 shows an example of a control flow at the time of reading a file. When it is necessary to read the file 71 from the storage system (step 70)
0), the control device 10 refers to the file table 11 and
It is determined whether the corresponding file 71 exists in the entire file area 31 (step 701). If the file 71 exists, the file 71 is read from the entire file area 31 and necessary processing is performed (step 702).

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

Further, the control device 10 updates the number of accesses to 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, the processing ends. If it exceeds α, it is determined whether the used capacity of the entire file area 31 exceeds β (step 708). If β has not been exceeded, the entire file 71 is written to an unused area of the entire file area 31 (step 709). If it exceeds β, the buffer storage capacity table 12 is referred to and the file partial area 3
It is determined whether or not the used capacity of No. 2 has exceeded γ (step 710). If it does not exceed γ, the file 72 to be destaged from the entire file area 31 to the partial file area 32 is determined using the LRU algorithm or the like, and the file 72 is stored in an unused area of the partial file area 32.
Of the file 72 in the file partial area 32 is set as an unused area, and the number of accesses to the file 72 in the file table 11 is reduced by 1 and updated (step 711). Thereafter, the file 71 is written to an unused area of the entire file area 31 (step 712).

If it exceeds γ in step 710, the file partial area 3 is
The file 73 to be destaged from the second to the secondary storage device 20 is determined, the area of the file 73 is set as an unused area, and the number of accesses to the file 73 in the file table 11 is reduced by 1 and updated (step 713). After that, the entire file area 31 to the partial file area 32
The file 72 is written in the unused area of. The area of the file 72 in the entire file area 31 is set as an unused area, and the number of accesses to the file 72 in the file table 11 is updated by subtracting 1 (step 711). The file 71 is written in an unused area of the entire file area 31 (step 712).

If it is determined in step 703 that a part of the file 71 does not exist in the file partial area 32, the secondary storage device 20 reads the file 71 so that the file 71 is read.
(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 file partial area 32 exceeds γ (step 716). If it does not exceed γ, a part of the head of the file 71 is written to an unused area of the file partial area 32 (step 717). γ
Is exceeded, the file 73 to be destaged from the file partial area 32 to the secondary storage device 20 is determined using the LRU algorithm or the like. The area of the file 73 is set as an unused area, and the file 73 of the file table 11 is used.
The number of times of access is reduced by 1 and updated (step 718). Thereafter, a part of the head of the file 71 is written into an unused area of the file partial area 32 (step 71).
7).

FIG. 5 shows an example of a control flow when updating a file. When the file 81 needs to be updated (step 800), the control device 10 refers to the file table 11 and determines whether the file 81 exists in the entire file area 31 (step 80).
1). If the file 81 exists, the entire file area 3
The first file 81 is updated (step 802). If the file 81 does not exist, it is determined whether or not a part from the beginning of the file 81 exists in the file partial area 32 by referring to the file table 11 (step 803).

If a part of the file 81 from the beginning exists in the file partial area 32, a part of the file 81 in the file partial area 32 from the beginning 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 instructed to read the remaining part of the file 81 (step 805). Secondary storage device 20
Reads out the rest of the file 81 and
And the control device 10 updates the remaining part of the file 81 (step 806). Further, the control device 10 updates the number of accesses to the file 81 in the file table 11 by adding 1 to the file, and determines whether the number of accesses exceeds α (step 807). If it does not exceed α, the processing ends.

If it exceeds α, the entire file area 31
Is greater than β (step 808). β
Otherwise, the entire file 81 is written to an unused area of the entire file area 31 (step 80).
9). If it exceeds β, it is determined whether the used area of the file partial area 32 exceeds γ by referring to the file table 11 (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 by using the LRU algorithm or the like, and the unused area of the partial file area 32 is shifted from the beginning of the file 82 by one. 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 to 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 the value exceeds γ in the check in step 810, the file 83 to be destaged from the partial file area 32 to the secondary storage device 20 is determined using the LRU algorithm or the like. File 8
The area of No. 3 is set as an unused area, and the number of accesses to the 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 an unused area of the file partial area 32, the area of the file 82 of the entire file area 31 is set as an unused area, and the file 8 of the file table 11 is used.
The number of accesses for 2 is updated by subtracting 1 (step 811). The file 81 is written in an unused area of the entire file area 31 (step 812).

If a part of the file 81 does not exist in the file partial area 32 in the check in the step 803, a command is issued to the secondary storage device 20 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 to the file 81 is incremented by 1 and updated (step 815). Further, the control device 10 refers to the buffer storage capacity table 12 and determines whether the used capacity of the file partial area 32 does not exceed γ (step 816). If it does not exceed γ, file 8
The first part of 1 is written to an unused area of the file partial area 32 (step 817). If γ is exceeded, LR
Using the U algorithm or the like, the file partial area 32 to 2
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 to the file 83 in the file table 11 is updated by subtracting 1 (step 818). Thereafter, a part of the head of the file 81 is written in an unused area of the file partial area 32 (step 817).

The new file 61 and the updated file 8
1 may be written to the secondary storage device 20 by referring to the staging identification flag of the file table 11 and determining whether to perform the processing in real time or offline in consideration of the required performance of the system.

In this embodiment, the secondary storage device 20 is described as a fixed medium storage device. However, an automatic medium exchange type storage device (drive device, automatic medium exchange device, However, those skilled in the art can easily understand the present embodiment by using the present embodiment. Further, the format of the tables and the example of the control flow used in the present embodiment are merely examples, and can be arbitrarily designed according to a specific implementation method of the present invention.

[0028]

As described above, according to the present invention,
The whole of a part of the files stored in the secondary storage means and a part of the remaining part of the files are stored in the buffer storage means, and when a desired file is accessed, the It is determined whether or not a desired file is stored in the buffer storage means, and when the entirety of the desired file is stored in the buffer storage means,
The entire desired file is read from the buffer storage means, and when a part of the desired file is stored in the buffer storage means, a part of the desired file is read from the buffer storage means and the remaining part of the desired file is read. When the desired file is not stored in the buffer storage means, the desired file is read from the secondary storage means.
Since control is performed so as to read from the next storage means, a large number of files can be stored in the buffer storage means as compared with the conventional method, and the hit rate for the files stored in the buffer storage means is dramatically increased. When a part of a desired file is stored in the buffer storage unit, the secondary storage unit is accessed while the desired file is being read from the buffer storage unit. The remaining part of the desired file can be read from the means without delay, and a decrease in system performance can be prevented. Also, the file stored in the buffer storage means is determined by the number of accesses,
For example, when an incorrect file is accessed (such access is usually performed only once), the staging of the wrong file in the buffer storage unit can be prevented, and the buffer storage unit can be effectively used. .

[Brief description of the drawings]

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

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

FIG. 3 is a flowchart showing an operation at the time of writing a file in the storage system control method of FIG. 1;

FIG. 4 is a flowchart showing an operation at the time of reading a file in the storage system control method of FIG. 1;

FIG. 5 is a flowchart showing an operation at the time of updating a file in the storage system control method of FIG. 1;

[Explanation of symbols]

 Reference Signs List 10 control device 11 file table 12 buffer storage device table 30 buffer storage device 31 entire file area 32 partial file area

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G06F 3/06

Claims (1)

(57) [Claims] 1. A large-capacity secondary storage means for storing all files, a part of the files stored in the secondary storage means, and the whole of the files stored in the secondary storage means. A high-speed buffer storing means for storing a part of the remaining files among the files being read, and when the desired file is accessed, the desired file is stored in the buffer storing means. Determining means for determining whether or not the entirety of the desired file is stored in the buffer storage means based on the determination result of the determining means; Read from the buffer storage means, when it is determined that a part of the desired file is stored in the buffer storage means,
A part of the desired file is read from the buffer storage means, and a remaining part of the desired file is read from the secondary storage means, and it is determined that the desired file is not stored in the buffer storage means. In the above, it is preferable that the apparatus further comprises: read control means for controlling the desired file to be read from the secondary storage means; and determination means for determining a file to be stored in the buffer storage means based on the number of accesses to the file. Characteristic storage system control method.