JPH0673113B2 - Disk cache device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a disk cache device, and more particularly to a disk cache device having a store-in function.

2. Description of the Related Art In a conventional magnetic disk device, each track on a magnetic disk medium is composed of a plurality of records, and when the data is written such that the arrangement or record length of these records is changed, the track capacity is exceeded by the writing of this data. In this case, an error report is made to the host device that has issued this write instruction as an illegal track format.

In recent years, a disk cache device has been put into practical use in order to reduce the difference between the processing speed of the central processing unit and the access speed of the magnetic disk device and improve the system performance. There is movement. The store-in operation means that the write instruction from the host device is processed only by the disk cache.
This store-in operation enables the writing process to be performed at high speed.

In such a conventional disk cache device, the write-in process could be performed at high speed by the store-in operation, but the limit of the track capacity on the disk cache could not be detected. There is a drawback in that the store-in operation cannot be applied to the magnetic disk device adopting the format.

The present invention has been made to eliminate the above-mentioned drawbacks of the conventional ones, and the store-in operation can be applied to a magnetic disk device adopting a variable-length record format.
An object is to provide a disk cache device that can improve the performance of an information processing system.

Configuration of the Invention A disk cache device according to the present invention is a disk cache device having a disk cache memory for storing track data which is stored in a disk recording medium and includes a plurality of record fields, wherein write data from a host device is the track. When writing from a predetermined record field of data, an addition unit that adds the data length of the track data up to immediately before the predetermined record field and the data length of the write data, the addition result of the addition unit, and the track data And a means for reporting an error to the upper device when the comparison means detects that the addition result exceeds the capacity of the track data.

Embodiment Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. Referring to FIG. 1, a disk cache device 1 according to an embodiment of the present invention includes an MPU (microproc) that incorporates a register 12.
essor unit) 11, a cache adapter 13, a cache memory 14, a host adapter 15, and a disk interface adapter 16.

A host processor 2 is provided as a host device of the disk cache device 1.
Are interconnected with the host adapter 15. Further, the disk controller 3 is interconnected to the disk interface adapter 16, and the magnetic disk devices 4 to 6 are interconnected to the disk interface adapter 16 via the disk controller 3.

The cache memory 14 is a semiconductor memory having a series of address spaces, and a plurality of buffer segments are logically assigned in the cache memory 14.

FIG. 2 is a diagram showing a track image on the disk medium (not shown) of the magnetic disk devices 4 to 6 in FIG.
In the figure, an HA (home address) field, a count field, a key field, and a data field for recording information are arranged on the track of the disk medium,
At the boundary of each field, there is a gap for continuously processing information on the disc medium that is constantly rotating.

Normally, the disk medium is allowed to have an appropriate number of defects per track, and the effective track capacity, which is the capacity for recording information, is calculated from the physical capacity of the track.
This is a value obtained by subtracting the gap capacity occupied by the defect in the track when the maximum number of defects is present within the allowable range.

FIG. 3 is a diagram showing a track image on the buffer segment of the cache memory 14 of FIG. Since this cache memory 14 is a semiconductor memory, the gap on the disk medium is removed from the buffer segment, and the fields are expanded so as to be adjacent to each other.

If a search / read / write instruction is issued from the host processor 2 to the disk cache device 1 before all the information on the target disk track is stored in the buffer segment of the cache memory 14, these search / read / write instructions are given. In contrast, MPU11 is a magnetic disk unit 4
~ 6 at the same time as the cache memory 14
The information on the target disc track is stored in the buffer segment in the format shown in FIG.

When a write instruction is input from the host processor 2 after all the information on the target disk track is stored in the buffer segment, the MPU 2 stores the search target field when executing the search instruction preceding the write instruction. All fields are traced in order from the HA field in order to obtain the address on the cache memory 14 that is stored.

In this process, add the gap length of the gap accompanying each field to the field length of the field that has passed until reaching the target field, and store the value in register 12 of MPU11. The field length of the information to be written and the gap length of the gap associated with the field are added to the stored value, and the addition result is compared with a predetermined effective track capacity. If the addition result exceeds the effective track capacity by this comparison, an error is reported to the host processor 2 as an invalid track format.

In this way, when the information is written from the target field by the write instruction from the host processor 2,
While the search instruction preceding this write instruction is being executed, the field length of the write instruction information and the gap length are added to the value obtained by adding the gap length to the field length up to the target field, and the addition result is valid. By comparing the track capacity with the track capacity, it becomes possible to detect the limit of the track capacity during the store-in operation. Therefore, the store-in operation is applied to the magnetic disk device adopting the variable length record format. be able to.

Further, since the store-in operation can be applied, the performance of the information processing system can be improved.

In the embodiment of the present invention, the case where the host processor 2 is connected as the host device has been described. However, this is not limited to any device as long as it is a device for writing to and reading from the magnetic disk devices 4-6. It is clear that also applies.

Further, although the magnetic disk device has been described in the embodiment of the present invention, it is obvious that the present invention can be applied to other disk devices, and the comparison with the effective track capacity is made with the value obtained by adding the data length. This may be done by subtracting the field length and gap length of each field from the effective track capacity, but is not limited to these.

As described above, according to the present invention, in the track data including a plurality of record fields, the data length of the write data is added to the data length immediately before the record field to be written, and the addition result and the track data thereof are added. The storage-in operation can be applied to the magnetic disk device that employs the variable-length record format, and the performance of the information processing system can be improved. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention, FIG. 2 is a diagram showing a track image on a disk medium of the magnetic disk device of FIG. 1, and FIG. 3 is a cache memory of FIG. It is a figure which shows the track image on a buffer segment. Explanation of symbols of main parts 1 ... Disk cache device 2 ... Host processor 4-6 ... Magnetic disk device 11 ... MPU 12 ... Register 14 ... Cache memory

Claims (1)

[Claims] 1. A disk cache device having a disk cache memory for storing track data including a plurality of record fields, which is stored in a disk storage medium, wherein write data from a host device is stored in a predetermined record field of the track data. Addition means for adding the data length of the track data up to immediately before the predetermined record field in the track data and the data length of the write data, and comparison for comparing the addition result of the addition means with the capacity of the track data. And a means for reporting an error to the higher-level device when the comparison means detects that the addition result exceeds the capacity of the track data.