JPH0520196A - Disk / Cash control unit - Google Patents

Abstract

(57) [Summary] [Purpose] Even if a power failure occurs, the disk cache that has not yet been written to the disk device.
To obtain a disk cache controller in which the data in memory is not lost. [Structure] The first disk cache storage unit A reads data from the host device 1, the second disk cache storage unit B writes data from the host device 1, and the control unit D writes the second disk data. The contents of the cache storage means B are controlled so as to be written also in the non-volatile storage means C having the same capacity as the second disk cache storage means B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk cache controller.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram of a conventional disk cache controller (hereinafter referred to as a conventional example), and FIG. 4 is a flow chart for controlling the operation of this conventional example. In FIG. 3, 1 is a host device, 2 is a disk cache memory 3
The disk cache control device 4 controls the disk device 5 and the disk cache control device 4 controls the disk device 5.

Next, the operation of this conventional example will be described with reference to FIGS. 3 and 4. 3 and 4, the disk cache control device 2 accessed by the higher-level device 1 (FIG. 3) determines whether the data is already stored in the disk cache memory 3 (step 41).

If the data requested by the host computer 1 is already stored in the disk cache memory 3 and the request from the host computer 1 is read (step 42).
Data is transferred from the disk cache memory 3 to the host device 1 (step 44), and if writing, data from the host device 1 is transferred to the disk cache memory 3 (step 43).

If the requested data is not stored in the disk cache memory 3 (step 41)
If the request from the host device 1 is read (step 45), the disk controller 4 reads data from the disk device 5 (step 48), and if the request from the disk cache memory 3 is write (step 48). 45) The data from the higher-level device 1 is transferred to the disk device 5 by the disk controller 4 (step 4).
6).

If the area is insufficient when transferring the data to the disk cache memory 3 (step 47), the least accessed data is replaced (step 50). At this time, if the data to be replaced is different from the data in the disk device 5, this data is transferred to the disk device 5 by the disk controller 4. Then, the data is read from the disk device 5 (step 51), transferred to the disk cache memory 3, and then transferred to the host device 1 (step 52).

[0007]

Since the conventional disk cache memory is controlled as described above, the disk cache memory that has not yet been written to the disk device when a failure such as a power supply occurs. There was a problem that the data inside was lost.

The present invention has been made to solve the above-mentioned problems, and it comprises a first disk cache storage means for reading the disk cache storage means,
A second disk cache storage means for writing and a non-volatile storage means of the same capacity as the second disk cache storage means;
The contents of the cache storage means are also written in the non-volatile storage means to obtain a disk cache control device in which data in the disk cache memory that has not yet been written in the disk device is not lost due to the occurrence of a failure such as a power supply. The purpose is to

[0009]

Therefore, in claim 1 of the present invention, the first disk for storing the data of the host device and, if necessary, the disk device and reading the data into the host device. Cache storage means, second disk cache storage means for storing data in the disk device as necessary, and writing from the host device; and nonvolatile storage having the same capacity as the second disk cache storage means And a second disc
It is an object of the present invention to achieve the above-mentioned object by a disk cache control device including control means for controlling the contents of the cache storage means to be written in the nonvolatile storage means.

According to a second aspect of the present invention, the contents of the second disk cache storage means from the host device are written into the disk device at any time when there is no access from the host device. It is an object of the present invention to achieve the above object by a disk cache control device according to claim 1, which transfers the contents of the disk cache storage means to the first disk cache storage means.

[0011]

In the disk cache control device according to claim 1 of the present invention, the data of the disk device is stored in the first disk cache storage means when necessary, and the data is read into the host device, and the second disk cache control device. The cache storage means stores the data of the disk device as necessary, the writing from the host device is performed, and the control means transfers the contents of the second disk cache storage means to the second disk cache storage means. It is controlled so that the data is also written in the non-volatile storage means having the same capacity.

According to a second aspect of the present invention, there is provided a disk cache control device according to the first aspect, wherein the contents of the second disk cache storage means from the host device are updated whenever there is no access from the host device. The contents of the second disk cache storage means are transferred to the first disk cache storage means while being written in the disk device.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a disk / disk according to an embodiment of the present invention.
FIG. 2 is a configuration diagram of the cache control device, and FIG. 2 is a flow chart for controlling the operation of this embodiment. In the figure, the same reference numerals as those used in the conventional example indicate the same or corresponding portions, and the duplicated description thereof will be omitted.

In this embodiment, which will be described below, the data of the disk device is stored in the disk cache memory as necessary, and when a hit is detected by the disk cache control device at the time of accessing the host device, the disk cache memory .Transfer of data in the memory to a host device, and when a mishit is detected, the data is read from the disk device, stored in the disk cache memory, and then the relevant data is transferred to the host device. Is.

In FIG. 1, A is a first disk cache storage means (hereinafter referred to as the first storage means), which is composed of a read disk cache memory 11.
It is a means for storing data in the disk device 5 and reading it into the host device 1 as required. B is a second disk cache storage means (hereinafter referred to as second storage means), which is composed of a write disk cache memory 12 and stores data of the disk device 5 as necessary,
This is means for writing from the host device 1.

Reference numeral C denotes a non-volatile storage means, which is composed of a non-volatile memory 13 having the same capacity as the second storage means B.
D is a control means and is a disk cache control device 2
It is a means for controlling so that the contents of the second storage means B are calibrated in step S4 and written in the nonvolatile storage means C.

Next, the operation of this embodiment will be described with reference to FIGS.
Will be explained. In FIG. 1 and FIG. 2, the disk cache control device 2 accessed from the host device 1
Is the disk cache memory 11 for reading or the disk cache memory 1 for writing
It is determined whether or not the data is already stored in No. 2 (step 21 in FIG. 2).

If the data requested by the host computer 1 is already stored in the read disk cache memory 11 and the request from the host device 1 is read (step 25), the read disk cache memory 11 is read. From the data to the higher-level device 1 (step 2
7). If the request from the host device 1 is a write (step 25), the read disk cache memory 1
The data from the host computer 1 is deleted, and the data from the host device 1 is transferred to the write disk cache memory 12 and the non-volatile memory 13.

In this case, it is judged whether or not there is a free space in the write disk cache memory 12 (step 2
6) If there is a free space, the data is transferred from the higher-level device 1 to the write disk cache memory 12 and the non-volatile memory 13 (step 30). If there is no free space at step 26, the data is replaced (step 28). ), The data is transferred from the host device 1 to the write disk cache memory 12 and the non-volatile memory 13 (step 29).

If the data requested by the host computer 1 is already stored in the write disk cache memory 12 (step 21) and the request from the host device 1 is read (step 22), the write disk・
The data is transferred from the cache memory 12 to the host device 1 (step 24). If the request from the host device 1 is a write (step 22), the data from the host device 1 is transferred to the write disk cache memory 12 and the non-volatile memory 13 (step 23).

Further, the disk cache controller 2 reads the data of the write disk cache memory 12 from the read disk cache memory 11 and the disk controller 5 when there is no access from the host device 1.
Transfer to the disk device 5 by
The data in the cache memory 12 and the non-volatile memory 13 are deleted.

Also, a read disk cache
If the area is insufficient when transferring data to the memory 11, the least accessed data is replaced. When the data is transferred to the write disk cache memory 12 and the area is insufficient, the least accessed data is replaced. At this time, the data to be replaced is transferred to the disk device 5 by the disk controller 4.

Further, if the data in the read disk cache memory 11 and the write disk cache memory 12 is lost due to a power failure or the like, the data in the nonvolatile memory 13 is written after the restoration. Transfer to the disk cache memory 12 for use.

As described above, according to this conventional example, it is possible to prevent the data in the disk cache memory that has not been written in the disk device from being lost due to a failure such as a power supply.

In the above embodiment, the read disk cache memory and the write disk cache memory are described as being physically separated. However, if they are logically separated, the same operation as in the above embodiment will be performed. It is possible to exert an effect.

Further, in the above embodiment, the nonvolatile memory having the same capacity as the writing disk cache memory is used. However, even if a volatile memory backed up by a battery or the like is used, the same operation as in the above embodiment can be obtained. It is possible to exert an effect.

[0027]

As described above, according to the present invention, the disk cache storage means includes the first disk cache storage means for reading and the second disk cache storage means for writing.
Data in the disk cache storage means that has not yet been written to the disk storage means device is provided because the nonvolatile storage means of the same capacity as the second disk cache storage means for writing is provided separately. Has the effect of not being lost due to a failure such as a power source.

[Brief description of drawings]

FIG. 1 is a block diagram of a disk cache control device according to an embodiment of the present invention.

FIG. 2 is a flowchart for controlling the operation of this embodiment.

FIG. 3 is a block diagram of a conventional disk cache controller.

FIG. 4 is a flowchart for controlling the operation of the conventional example.

[Explanation of symbols]

A first disk cache storage means B Second disk cache storage means C non-volatile storage means D control means 1 Upper device 2 Disk cache controller 4 Disk controller 5 disk device 11 Read disk cache memory 12 Disk cache memory for writing 13 Non-volatile memory The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (2)

[Claims] 1. A first disk cache storage means for storing data of a host device and a disk device as necessary, and reading the data into the host device, and storing data of the disk device as necessary. A second disk cache storage means for performing writing from the host device;
A control means having a nonvolatile storage means having the same capacity as the second disk cache storage means, and controlling the contents of the second disk cache storage means to be written also in the nonvolatile storage means. A disk cache control device comprising: 2. When there is no access from a host device,
The contents of the second disk cache storage means from the host device are written into the disk device at any time, and the contents of the second disk cache storage means are transferred to the first disk cache storage means at any time. The disk cache control device according to claim 1.