JP2975253B2 - Multiplexed volume device - Google Patents

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 provided with a cache memory and a data read process. The present invention relates to a multiplex volume apparatus suitable for a case where the number of times is larger than that of the write processing.

[0002]

2. Description of the Related Art Conventionally, in a computer system, a multiplexed volume device for storing data in a plurality of volumes and improving data integrity has been used in order to improve the reliability of the system.

In such a multiplexed volume apparatus, generally, two volumes are used, one is a primary volume, the other is a secondary volume, write processing is performed on both primary and secondary volumes, and read processing is performed on one of the volumes. From the beginning.

As a method of selecting a volume to be read in this case, there is the following known example.

Known example 1: Hitachi program product VOS3 disk dual write control program WDCP /
ES In this known example 1, one of three methods, that is, the primary volume is read with priority, the secondary volume is preferentially read, and the primary and secondary volumes are alternately read, can be selected and used.

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

[0007]

However, in the method of prior art 1 in which the primary volume or the secondary volume is preferentially read, the read processing is concentrated on only one volume, and the load is concentrated on one volume. However, there is a problem that input / output performance is deteriorated.

In the method of reading the primary and secondary volumes alternately in the first known example and the method of reading the smaller number of input / output instructions in the second known example, the volume in which data is stored is provided with a cache memory. In such a case, the following problem occurs.

That is, even when data to be read exists in the cache memory of one volume and there is 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 is longer than when the former volume is selected.

At this time, the same data is stored in the cache memories of both the primary and secondary volumes, and there is a problem that the cache memory that can be used for other data is wasted.

These problems are particularly serious when continuous data is read by a plurality of read instructions.

An object of the present invention is to provide a multiplexed volume apparatus capable of averaging the load of read processing for each volume, effectively using a cache memory provided for each volume, and enabling high-speed read processing. It is to be.

[0013]

In order to achieve the above object, the present invention basically comprises a plurality of volumes.
Each volume to a fixed partial unit (eg, cylinder)
Volume determining means for determining a volume to be divided and to perform a read process; and
A read priority volume selection table for storing for each partial unit; and a read processing execution means for obtaining a volume for performing a read process from the read priority volume selection table at the time of executing a read command and executing the read process from the obtained volume. It is a thing.

Further, when data is stored in only a part of a volume or when data exists in the cache memory of all volumes by a write process,
In the case where load averaging cannot be performed sufficiently depending on the setting value of the read priority volume selection table, the read priority volume selection table is updated at regular time intervals or at a constant read time according to occurrence of read processing or write processing.
It starts every processing count and changes dynamically.

[0015]

According to the above-mentioned means, a plurality of volumes can be fixed.
For each partial unit divided into partial units (for example, cylinders), a volume on which read processing is to be executed is determined.
In this case, the volumes corresponding to the respective partial units are determined so that the read processing load on each volume is averaged, for example. Then, for a read command for each partial unit, a volume for which read processing is to be executed is determined from the read priority volume selection table, and read processing is executed for that volume.

Therefore, the load of the read processing for each volume can be averaged. Furthermore, the cache memory provided for each volume can be used effectively.

Here, the meaning of effective use means that, in response to a read instruction, data that already exists in the cache memory is read, thereby shortening the read processing time and doubling or multiplexing the data. It does not have it on the cache memory.

[0018]

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

FIG. 1 is a block diagram showing an embodiment of the present invention, wherein 101 is an instruction processor, 102 is an input / output processor, 103 is a read count 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
To 113 are first to third volume control devices;
Reference numeral 123 denotes each of the first to third volume control devices 111 to
Cache memories 131 to 133 corresponding to the volume controllers 113 to 133 are first to third volumes corresponding to the volume controllers 111 to 113, respectively.
1 to 133 store the same data.

In this case, the first to third volumes 13
Reference numerals 1 to 133 each include, for example, a magnetic disk memory device.

FIG. 2 shows 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. FIG. 2A shows an initial state, and FIG. 2B shows an operating state.

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

In this case, if "0" is set as the volume number 1041, it indicates that reading from any volume is possible.

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

FIG. 2B shows that the number of times of read processing during a fixed time immediately before the issuance of a read instruction is equal for each of the cylinder numbers 1 to i, i + 1 to j, j + 1 to 3n. 3 shows the contents when i and j are determined.

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

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.
03 stores that the total number of read times for 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, the load on the read processing can be averaged by reading each of the volumes 131 to 133 ten times. Volume numbers are set so that data of 〜3, 4、４5, and 6〜9 are read from the volumes 131１〜133, respectively.

FIG. 4 is the same as that of FIG.
The total number of read times for each of 4 to 5 is 10 times in total. Since no read command has been issued to cylinders 6 to 9, the volume number is "0".

For the cylinders for which the volume number "0" is set, the read command was not issued at all or the data was written to the cache memories 121 to 123 of all the volumes at the time of the write command. Indicates that reading may be started from any volume. At the time of read processing for a cylinder from which data can be read,
Or a volume with a small number of input / output instructions is selected as shown in the second prior art. As a result, even when the distribution of the number of times of read processing for each cylinder suddenly changes because a data set is newly allocated to an 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.
13 is a flowchart showing the processing contents of the step 05.

First, after setting the cylinder number to "1" (step 501), the number of reads for the cylinder with the number "1" of each of the volumes 131 to 133 is extracted from the read number storage table 103, and the number of reads is "0". It is determined whether or not this is the case (step 502).

If the number of reads 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 total number S of read times from the cylinder number “1” to the cylinder number whose volume number is to be determined at present, and the total number T of read times for the cylinders of all cylinder numbers are stored in the read number storage table 103. Determined from the stored contents, (S / T) · V (1) A volume number corresponding to the number of reads for each cylinder is determined by (V = the number of volumes).

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

This step 503 corresponds to volume determination means.

Next, "1" is added to the cylinder number to update the cylinder number (step 505), and it is determined whether or not the volume numbers for all the cylinders have been determined (step 506). , Step 5
Returning to step 02, the volume number is determined for the next cylinder.

When the determination of the volume numbers of all the cylinders is completed, the number-of-reads storage table 103 is cleared to "0" (step 507).

The management program 105 is started every time a fixed time elapses or when the number of times of read processing reaches a certain value.
4 is dynamically updated while the system of the embodiment is operating.

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

First, in the read processing, in response to a read request for the cylinder with the cylinder number n, the contents of the read priority volume selection table 104 are taken out, and it is determined whether or not the volume number corresponding to the cylinder number n is "0". (Step 601).

If the volume number is not "0", a read command is issued to the volume of the 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) Then, the volume number selected at this time is set in the read priority volume selection table 104 so that the read processing for the cylinder is performed on 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 process, all the cache memories 121 to 123
It is determined whether or not the system is performing a control of writing data to the memory (step 701). In the case of the system for writing all data, when reading the data immediately, Since the volume may be read, the volume number in the read priority volume selection table 104 is set to “0” (Step 702), and then a write command is issued to all the volumes (Step 703).

However, in the case where the write method is not all write, the write command is issued to all volumes without setting the volume number to “0”.

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

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

FIG. 8 is a block diagram showing another embodiment of the present invention. 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 where the device is provided in the device 02.

By providing the read priority volume selection table 104 in the input / output processor 102 as described above, the selection of the volumes 131 to 133 can be performed by the input / output processor 102, so that 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 volume division unit. However, the storage area is physically stored in a magnetic tape device, a flexible disk device, a readable / writable optical disk device, or the like. If it can be used by being divided into a plurality of areas, it can be applied to all of them.

Although the volume for each division unit is determined to be averaged, it is not always necessary to average the volume. For example, for a plurality of volumes whose input / output speed is slower than the others, the number of reads is The division unit may be allocated so as to reduce the number. As a result, the input / output performance can be leveled from the viewpoint of the entire volume, and the overall input / output performance can be improved even if the input / output speed varies.

[0053]

As described above, in the present invention, basically, a plurality of volumes storing data of the same contents are stored.
Dividing each volume constituting a constant partial unit (e.g. a cylinder), and a read priority volume selection table that stores the volume determining means for determining a volume of performing a read process, the number of the determined volume for each of the partial unit And a read processing executing means for executing a read processing on the volume by obtaining a volume for performing the read processing from the read priority volume selection table when the read command is executed. And the input / output performance of the entire volume can be improved.

Also, by starting the read priority volume selection table every fixed time or every certain number of read processes and dynamically changing it, the cache memory provided for each volume can be used effectively. This has the effect of enabling high-speed read processing.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one 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 processing contents of a read priority volume selection table management program.

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

FIG. 7 is a flowchart showing 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 an 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 to 123: Cache memory, 131 to 133: Volume.

Continued on the front page (72) Inventor Susumu Suzuki 5030 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Hitachi, Ltd. Software Development Division (56) References JP-A-3-253933 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) G06F 3/06

Claims (3)

(57) [Claims] 1. A multiplexed volume device in which data having the same content is stored in a plurality of volumes and each volume is provided with a cache memory , wherein each volume constituting said plurality of volumes is divided into a fixed partial unit. Volume determining means for determining a volume to be subjected to read processing, a read priority volume selection table for storing the determined volume number for each partial unit, and reading from the read priority volume selection table when a read command is executed. A multiplexing volume apparatus comprising: a read processing execution unit that obtains a volume on which processing is to be performed and executes read processing from the obtained volume. Wherein said volume determination means, multiplexed volume device according to claim 1, wherein the read processing count for each volume and determining a volume for performing read processing to average. 3. A multiplexed volume device according to claim 1 or 2, characterized in that activating the volume determining means for each or every constant lead processing count a predetermined time.