JPS6331806B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to cache memory systems for disks in data processing systems.

In general, the speed of main memory (especially access
Since the processing time is slow, a high-speed buffer memory (called a cache memory) is placed between these two to prevent the processing speed from decreasing due to the main memory. A similar idea is applied between a magnetic disk device (hereinafter simply referred to as a disk) and the computer itself, and it has been proposed that a buffer memory (hereinafter referred to as a disk cache) be placed between the two to effectively shorten access time. ing.

However, in the conventionally proposed disk cache, for example, as shown in FIG. 3 is connected, and the disk cache control section performs the control. and,
A record in the disk device 4 that has been accessed once from the computer main body is stored in the disk cache memory section 3 under the control of the disk cache control section 2, and then in response to a request for the same record, the record is stored in the disk cache memory section 3 under the control of the disk cache control section 2. The contents of the request record are read from the cache memory section 3 and sent to the computer main body, without accessing the disk device 4. In addition,
This control is performed by the disk cache control device 2. The disk cache memory unit 3 has faster memory (CCD,
(bubble memory, IC memory, etc.), and even if its capacity is small, part of the access to the disk device 4 can be completed by accessing only the disk cache memory section 3. This has the effect of reducing the average value of access time to 4.

However, this conventional method has the following drawbacks.

This results in a special and expensive disk cache control unit 2. It is difficult for multiple disk controllers to share one disk cache. If the disk cache control device 2 breaks down, the disk device 4 becomes unusable. To avoid this, it is necessary to bypass the failed disk cache control device 2, such as by providing another path from the disk control device 1 to the disk device 4.

SUMMARY OF THE INVENTION An object of the present invention is to provide a disk cache system that can utilize a disk cache without using a dedicated disk cache control device.

The system of the present invention includes: a main storage device; a disk cache memory device; a data transfer device that transfers data between the main storage device and the disk cache memory device; an input/output channel for transferring data with at least one of the storage memory devices; and an input/output channel for instructing data transfer between the input/output channel and the main storage device and the disk cache memory device or for data transfer to the data transfer device. and an output processing device.

Next, the present invention will be explained in detail with reference to the drawings.

An embodiment of the present invention shown in FIG. 2 includes an arithmetic processing unit 11, an input/output processing unit 12, a system interface circuit 13, a main storage unit 14, a disk cache memory unit 3, an input/output channel 16, and a disk control unit. 1, a disk device 4, and a data transfer device 19.

The arithmetic processing unit 11, input/output processing unit 12, and input/output channel 16 all access the main storage device 14 via the system interface circuit 13.

Next, the operation of the present invention will be explained. When reading data from the disk device 4 when a disk cache is not used, the arithmetic processing unit 11 sends a disk read request and necessary information (for example, where in the main storage device 14 to store the data) to the input/output processing device. 12, the input/output processing device 12 makes preparations necessary for its operation (for example, preparation of a channel program) based on the input/output processing device 12, and outputs the input/output channel 16.
and the disk device 4 via the disk controller 1.
Start up and read the data. In this case, the read data is sent via the input/output channel 6 directly to the location in the main memory 14 requested by the arithmetic processing unit 11. When using a disk cache in this system, it is necessary to add a disk cache memory device 3 and a data transfer device 19. Although the disk cache memory device 3 does not necessarily use the same elements as the main memory device 14, it is connected to the system interface circuit 13 with matching interface conditions (access times, etc. may be different), and the system interface circuit 13, in particular, the input/output channel 16. The data transfer device 19 is a disk cache memory device 3, and the main storage device 4 is a disk cache memory device 3.
For example, data read from the disk cache memory device 5 can be written to the main storage device 14, and vice versa.

Therefore, the data transfer device 19 does not need to be directly connected to the system interface circuit 13, and may be connected at the end of the input/output channel, for example, as shown in FIG.

When using disk cache in this configuration,
When the input/output processing unit 12 receives a disk read command from the arithmetic processing unit 11, it checks whether the requested record exists in the disk cache 5. If the record exists, the record is transferred to the specified location in the main storage device 14 via the data transfer device 19, and the series of operations is completed.
If the requested record does not exist in the disk cache memory device 3, the requested record is read from the disk device 4 via the input/output channel 6 and the disk controller 1 and stored in the disk cache memory device 3. The data is stored in the storage memory section 3. If there is no free space in the disk cache memory section 3, the record with the lowest priority in the disk cache memory section 3 is evicted and stored (this is similar to the cache in a normal arithmetic processing unit). ).

Next, the requested record is transferred from the disk cache memory section 3 to the specified storage location in the main storage device 14 via the data transfer device 19, and the series of operations is completed. If there is a request to read the same record later, the access time can be shortened by reading it from the disk cache memory unit 3 using the same operation as described above.

In the present invention, it is possible to use the same memory device as the main storage device 14 as the disk cache memory. Generally, when the main storage device 14 is expanded, the increased memory cannot be used to improve the system's processing capacity without changing the software, but when used as a disk cache, Since it is not directly visible to the software, the processing power of the system can be improved without changing the software.

The data transfer device has a configuration as shown in FIG. 4, and data given through one interface circuit 191 is given once to a buffer circuit 193 equipped with a small capacity memory, and then transferred to another interface circuit 193. The signal is sent out via a circuit 192.

The present invention provides a dedicated disk drive in an information processing device equipped with an input/output processing device by configuring data transfer between a disk cache and a main memory and between a disk cache and an input/output channel. This has the advantage that a disk cache can be introduced without using a cache control device.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional disk cache system, FIG. 2 is a diagram showing an embodiment of the present invention, and FIG. 3 is a diagram showing the system interface circuit 1 of FIG. 2.
3. A diagram showing the connection relationship between the input/output channels 15, 17, the disk control device 1, and the data transfer device 19, and FIG. 4 is a diagram showing the data transfer device of FIG. 2. 1 to 4, 1...disk control device, 2...disk cache control device, 3...disk cache memory unit, 4...disk device,
11... Arithmetic processing device, 12... Input/output processing device, 1
3... System interface circuit, 14... Main storage device, 15, 16, 17... Input/output channel, 19
...Data transfer device, 191, 192...Interface circuit, 193...Buffer circuit.

Claims (1)

[Scope of Claims] 1. A main storage device, a disk cache memory device, a data transfer device that transfers data between the main storage device and the disk cache memory device, a system interface circuit, and a disk. a control device, a disk device connected to the disk control device, and data transfer between at least one of the main storage device and the disk cache memory device and the disk control device via the system interface circuit. 1. A disk cache system comprising: an input/output channel for performing data transfer; and an input/output processing device for instructing the input/output channel and the data transfer device to transfer data.