JPH07230358A - Multiplexed volume device - Google Patents

Abstract

PURPOSE:To average the loads of read processing to respective volumes by obtaining the volume to be subjected to read processing from a read priority volume selection table to execute the processing in the case or a read instruction to each division unit. CONSTITUTION:When the number of cylinders in first to third volumes 131 to 133 is 3n in total, they are so set that the volume 131 is selected for cylinder numbers l to (n) and the volume 132 is selected for cylinder numbers n+1 to 2n and the volume 133 is selected for cylinder numbers 2n+1 to 3n. when the read instruction is issued to certain data, the volume corresponding to the cylinder number where data to be read exists is selected by a read priority volume selection table 104. Cylinder numbers are so determined that their frequencies in read processing for a certain time just after the issue of the read instruction are equalized, thereby averaging the loads of read processing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplexed volume device for storing data of the same content in a plurality of volumes in an electronic computer system or the like, and more particularly to a volume device equipped with a cache memory and for reading data. The present invention relates to a multiplexed volume device suitable when the number of times is greater than that of write processing.

[0002]

2. Description of the Related Art Conventionally, in a computer system, in order to improve the reliability of the system, a multiplexed volume apparatus is used which stores data in a plurality of volumes to improve data integrity.

In such a multiplexed volume device, generally, two volumes are used, one is a primary volume and the other is a secondary volume, and write processing is performed on both primary and secondary volumes, and read processing is performed on either volume. I am going to start from.

As a method for selecting a volume to be read in this case, there are the following known examples.

Known example 1; Hitachi Ltd. product VOS3 disk double writing control program WDCP /
ES In this publicly known example 1, one can be selected and used from three methods, that is, the primary volume is preferentially read, the secondary volume is preferentially read, and the primary and secondary volumes are alternately read.

Known example 2; Japanese Patent Laid-Open No. 4-186422 In this known example 2, the numbers of input / output instructions in the waiting state are compared, and the volume having the smaller number is read.

[0007]

However, in the method of prioritizing reading of the primary volume or the secondary volume of the known example 1, the read processing is concentrated on only one volume and the load is biased to one volume. However, there is a problem that input / output performance is deteriorated.

In the method of alternately reading the primary and secondary volumes of the known example 1 and the method of reading the volume having the smaller number of input / output instructions in the known example 2, the volume storing the data is equipped with the cache memory. In this case, the following problems will occur.

That is, even if there is data to be read in the cache memory of one volume and no data to be read in the cache of the other volume, the latter volume is selected. However, when the latter volume is selected, there is a problem that the read processing time becomes longer than when the former volume is selected.

Further, at this time, the same data is held in the cache memories of both the primary and secondary volumes, and there is a problem that the cache memory originally used for other data is wasted.

These problems become particularly serious when continuous data is read by a plurality of read commands.

An object of the present invention is to provide a multiplexed volume apparatus capable of averaging the load of read processing for each volume and effectively utilizing the cache memory equipped in each volume to enable high-speed read processing. It is to be.

[0013]

In order to achieve the above object, the present invention basically divides a plurality of volumes storing data of the same content into units of a certain size (for example, cylinders). For each division unit, a volume determination unit that determines a volume for which a read process should be executed, a read priority volume selection table that stores the number of the determined volume for each division unit, and a read command for each division unit A read process execution unit is provided which obtains a volume to execute the read process from the read priority volume selection table and executes the read process on the volume.

Furthermore, when data is stored in only a part of the volume, or when data exists in the cache memory of all volumes due to write processing,
Depending on the setting value of the read priority volume selection table, if the load cannot be averaged sufficiently, the read priority volume selection table may be read every time a certain period of time or the number of reads is changed according to the occurrence of read processing or write processing. It was changed dynamically every time a certain number of times was reached.

[0015]

According to the above means, the volume to be read is determined for each division unit obtained by dividing a plurality of volumes into units of a certain size (for example, cylinders). In this case, the volume corresponding to each division unit is determined so that the read processing load on each volume is averaged, for example. Then, in response to the read command for each division unit, the volume for which the read process should be executed is obtained from the read priority volume selection table, and the read process is executed for that volume.

Therefore, the load of read processing for each volume can be averaged. Further, the cache memory equipped in each volume can be effectively used.

Here, to effectively use the data means that the read processing time is shortened by reading the data already existing in the cache memory in response to the read instruction, and the data is duplicated or multiplexed. It is not held in the cache memory.

[0018]

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

FIG. 1 is a block diagram showing an embodiment of the present invention. 101 is an instruction processor, 102 is an input / output processor, 103 is a read number storage table, 104 is a read priority volume selection table, and 105 is a read priority volume. Selection table management program, 106 is a read processing program, 107 is a write processing program, 111
˜113 are first to third volume control devices, 121˜
Reference numerals 123 to 111 denote first to third volume control devices, respectively.
A cache memory corresponding to 113, 131 to 133 are first to third volumes corresponding to the volume control devices 111 to 113, and 13 of the first to third volumes.
Data of the same contents are stored in 1 to 133.

In this case, the first to third volumes of 13
1 to 133 are composed of, for example, magnetic disk memory devices.

FIG. 2 shows the details of the read priority volume selection table 104. The left column of the table 104 stores the cylinder number 1040, and the right column stores the volume number 1041 to be selected for the read command. 2A shows the initial state and FIG. 2B shows the operating state.

Here, in the initial state of FIG. 2A, if the total number of cylinders 131 to 133 of the first to third volumes is 3n, the volume 131 is assigned to the cylinder numbers 1 to n. The volumes n + 1 to 2n are set to select the volume 132, and the cylinder numbers 2n + 1 to 3n are set to select the volume 133.

In this case, if "0" is set as the volume number 1041, it indicates that any volume can be read.

Now, when a read command is issued for certain data, the read priority volume selection table 104 selects the volume corresponding to the cylinder number in which the data to be read exists.

In FIG. 2B, the number of read processes during a fixed time immediately before the read command is issued is equal to each of the cylinder numbers 1 to i, i + 1 to j, and j + 1 to 3n. Shows the contents when i and j are defined.

An example of the read priority volume selection buffer in which i and j are defined as described above will be described below with reference to FIGS. 3 and 4.

FIG. 3 shows an example of the read priority volume selection table 104 and the read count storage table 103 according to the read count. The read count storage table 1
In 03, it is stored that the total number of read times of each of the cylinders 1 to 3, 4 to 5, and 6 to 9 is 10 times.

In the case of such a read history, by reading each of the volumes 131 to 133 10 times, the load on the read processing can be averaged. Therefore, in the read priority volume selection table 104, the cylinder 1 Volume numbers are set so that the data of ~ 3, 4-5, and 6-9 are read from the volumes 131-133, respectively.

The same applies to FIG. 4, in which the cylinders 1, 2 to 3,
The total number of read times of 4 to 5 is all 10. Further, since the read command has not been issued to the cylinders 6 to 9, the volume number is set to "0".

For a cylinder for which "0" is set as the volume number, no read command is issued at all, or data is written to the cache memories 121 to 123 of all volumes at the time of a write command. Indicates that it is possible to read from any volume. Known example 1 at the time of read processing for a cylinder that can read from any volume
The volume is cyclically selected as shown in, or the volume with a small number of input / output instructions is selected as shown in the known example 2. As a result, even if the distribution of the number of read processes for each cylinder changes abruptly because a new data set is allocated to the unused area of the volume, the change can be followed.

FIG. 5 shows a management program 1 started to manage the read priority volume selection table 104.
It is a flowchart which shows the processing content of 05.

First, after the cylinder number is set to "1" (step 501), the read count for the cylinder of the number "1" of each volume 131 to 133 is retrieved from the read count storage table 103, and the read count is "0". It is determined whether or not (step 502).

If the read count is "0", the volume number for the cylinder is set to "0" (step 50).
4).

However, if the read count is not "0",
The volume number is determined according to the read count (step 503).

That is, the cumulative number S of reads from the cylinder number “1” to the cylinder number for which the volume number is currently determined and the total number T of reads for all cylinder numbers are stored in the read number storage table 103. Obtained from the stored contents, (S / T) · V (1) (V = volume number) determines the volume number according to the number of reads for each cylinder.

In this case, the fractional part of the calculation result of the above equation is rounded up.

This step 503 corresponds to volume determining means.

Next, "1" is added to the cylinder number to update the cylinder number (step 505), and it is judged whether the volume numbers for all cylinders have been decided (step 506). , Step 5
Returning to 02, the volume number determination process for the next cylinder is performed.

When the volume numbers of all the cylinders are determined, the read number storage table 103 is cleared to "0" (step 507).

The management program 105 is started every time a certain period of time elapses or when the number of read processes reaches a certain value, and the read priority volume selection table 10
4 is dynamically updated during the operation of the system of the embodiment.

FIG. 6 is a flowchart showing the processing contents of the read processing program 106.

First, in the read processing, the contents of the read priority volume selection table 104 are fetched in response to a read request for the cylinder of cylinder number n, and it is judged whether the volume number corresponding to that cylinder number n is "0". (Step 601).

If the volume number is not "0", a read command is issued to the volume of that volume number (step 606). Prior to this, the value of the read count for cylinder n in the read count storage table 103 is updated (step 605).

On the other hand, if the volume number is "0", the volume is selected by the conventional method (step 60).
3) After that, the volume number selected at this time is set in the read priority volume selection table 104 so that the read processing for that cylinder is processed by the same volume thereafter (step 604).

FIG. 7 is a flowchart showing the processing contents of the write processing program 107. First, in the write processing, all cache memories 121 to 123
It is determined whether or not the method is such that data is controlled to be written to (step 701), and in the case of the method of writing to all, when reading the data immediately after, in terms of cache memory usage efficiency, Since the volume may be read from, the volume number of the read priority volume selection table 104 is set to "0" (step 702), and then the write command is issued to all the volumes (step 703).

However, if it is not the method of writing to all, the write command is issued to all the volumes without setting the volume number to "0".

As described above, since the read processing for certain data within the fixed time is executed only by one of the volumes 131 to 133, the cache memory 12
If the cache memories 121 to 123 do not have multiple data on the cache memory and data exists on the cache memories 121 to 123, the read processing can be executed at high speed because the cache memories 121 to 123 are used.

Further, since the read priority volume selection table 104 is updated at the frequency of the read processing for each of the volumes 131 to 133 or at regular intervals, the load for the read processing can be averaged.

FIG. 8 is a block diagram showing another embodiment of the present invention, in which the read priority volume selection table 104 and the read count storage table 103 are stored in the input / output processor 1.
FIG. 2 is a configuration diagram in the case of being provided in 02.

As described above, by providing the read priority volume selection table 104 in the input / output processor 102, the volumes 131 to 133 can be selected by the input / output processor 102, so the load on the instruction processor 101 is reduced. can do.

In the embodiment, the cylinder of the magnetic disk device is taken as an example of the unit of volume division, but a storage area such as a magnetic tape device, a flexible disk device, and a readable / writable optical disk device is a physical storage area. If it can be divided into a plurality of areas and can be used, it can be applied to all of them.

Further, although the volume for each division unit is determined to be averaged, it is not always necessary to average it. For example, for a volume having a slower input / output speed than others, the read count is You may make it allocate a division unit so that it may become small. As a result, the input / output performance of the entire volume can be leveled, and the overall input / output performance can be improved even if the input / output speed varies.

[0053]

As described above, according to the present invention, basically, a plurality of volumes storing data of the same content are divided into units of a fixed size (for example, cylinders), and the read is performed for each divided unit. From the read priority volume selection table for a read command for each division unit, a volume determination means for determining a volume to execute processing, a read priority volume selection table for storing the number of the determined volume for each division unit. Since the read processing execution means for determining the volume to execute the read processing and executing the read processing for the volume is provided, the load of the read processing in each volume is averaged and the input / output performance of the entire volume is improved. Can be made.

Further, by dynamically changing the read priority volume selection table every time a predetermined time elapses or each time the number of reads reaches a certain number, the cache memory equipped in each volume is effectively used and high speed is achieved. This has the effect of enabling read processing.

[Brief description of drawings]

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

FIG. 2 is a detailed configuration diagram of a read priority volume selection table.

FIG. 3 is a diagram showing an example of the contents of a read priority volume selection table.

FIG. 4 is a diagram showing another example of the contents of a read priority volume selection table.

FIG. 5 is a flowchart showing the processing contents of a read priority volume selection table management program.

FIG. 6 is a flowchart showing the processing contents of a read processing program.

FIG. 7 is a flowchart showing the processing contents of a write processing program.

FIG. 8 is a configuration diagram showing a configuration of another embodiment when a read priority volume selection table is provided in the input / output processor.

[Explanation of symbols]

101 ... Instruction processor, 102 ... Input / output processor,
103 ... Read count storage table, 104 ... Read priority volume selection table, 105 ... Read priority volume selection buffer management program, 106 ... Read processing program, 107 ... Write processing program, 111-1
13 ... Volume control device, 121-123 ... Cache memory, 131-133 ... Volume.

Claims (3)

[Claims] 1. A multiplexed volume apparatus for storing data of the same content in a plurality of volumes, wherein a volume to which a read process is to be executed is divided into units of a plurality of units each of which is divided into units of a certain size. Volume determining means for determining, a read priority volume selection table for storing the number of the determined volume for each division unit, and a volume for which a read process is executed from the read priority volume selection table for a read command for each division unit And a read process executing means for executing a read process on the volume. 2. The multiplexed volume apparatus according to claim 1, wherein the volume determining means determines a volume to execute a read process so that the number of read processes for each volume is averaged. . 3. The volume deciding means is activated every fixed time or every time the number of read processing reaches a fixed value, and the volume number in the read priority volume selection table is dynamically changed. 2. The multiplexed volume device according to 2.