JP2570005B2 - Peripheral device controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a peripheral device control device, and more particularly to an error recovery process by a peripheral device control device having a data compression mechanism.

[0002]

2. Description of the Related Art In general, a cartridge magnetic tape control device for controlling a cartridge magnetic tape device having poor start and stop characteristics has a large-capacity data buffer for compensating a start and stop time of a magnetic tape. In this type of magnetic tape control device, data transfer between a host device and a magnetic tape device is performed asynchronously.

As described above, a system including a magnetic tape device and a magnetic tape control device for controlling the magnetic tape device is generally called a cartridge magnetic tape subsystem.
A failure occurred during the write processing of the data sent from the host device, and it became necessary to rewrite via another magnetic tape control device or to perform rewrite using another magnetic tape device At this time, the higher-level device reads the data left unwritten in the data buffer once into the higher-level device, and then retransmits and writes the data via the target magnetic tape control device or magnetic tape device. There is a need.

[0004] Such magnetic tape subsystems include:
A data compression mechanism for efficient use of a magnetic tape or a plurality of data blocks (logical data blocks) sent from a higher-level device are automatically connected, and auto-blocking is written on the tape as one block (physical data block). Some are provided with a mechanism.

Referring to FIG. 4, in the magnetic tape subsystem, blocks 401 to 401 are provided on the magnetic tape in the normal mode.
Write 401 (FIG. 4A).

On the other hand, when the data compression mechanism and the auto-blocking mechanism are used together, the block 4
05 and 406 are written (FIG. 4B). Here, reference numerals 407 to 412 denote logical blocks which are units of data blocks viewed from the host system.

[0007]

As described above, in the magnetic tape control device in which the data compression mechanism is provided between the connection control unit for the host device and the data buffer, the compressed data is stored in the data buffer. As a result, the host device may seem to store a data amount exceeding the physical capacity in the data buffer.

When a failure occurs during the writing process and the higher-level device needs to collect the unwritten data from the data buffer as described above, the conventional magnetic tape control device deletes the compressed data in the data buffer. It is expanded and transferred to the host device. For this reason, there is a problem that the host device needs to secure a large-capacity storage area for temporarily storing a large amount of collected data. Further, there is a problem that the loss time for transferring a large amount of data increases.

An object of the present invention is to provide a peripheral device control device in which a host device does not need to secure a large-capacity storage area.

It is another object of the present invention to provide a peripheral device control device which requires a short data transfer time.

[0011]

According to the present invention, there is provided a peripheral device control device which is located between an external storage device and a host device and controls data transfer between the host device and the external storage device. A buffer, first storage means for storing data from the higher-level device as compressed data in the data buffer, and the external storage device using the compressed data as first transfer data asynchronously with a write operation to the data buffer. First transfer means for transmitting the compressed data in the data buffer in a compressed state as second transfer data to the higher-level device in response to a request from the higher-level device; And a second storage unit for storing the second transfer data transferred again from the storage unit as compressed data in the data buffer. Instrument control device is obtained.

Further, according to the present invention, in a peripheral device control device which is located between an external storage device and a host device and controls data transfer between the host device and the external storage device, a data buffer; First storage means for combining a plurality of logical data blocks sent from the device into one data block and storing the combined data block in the data buffer, and the combined data block asynchronously with a write operation to the data buffer A first transfer means for sending the first transfer data as the first transfer data to the external storage device, and a second transfer of the combined data block in the data buffer in response to a request from the higher-level device when the write processing is abnormally interrupted. Second transfer means for transferring the data as data to the higher-level device; and transferring the second transfer data transferred again from the higher-level device to the higher-level device. Peripheral equipment control device is obtained, characterized in that it comprises a second storage means for storing in said data buffer as Naruzumi data block.

[0013]

Next, the present invention will be described based on embodiments.

Referring to FIG. 1, the illustrated magnetic tape subsystem includes magnetic tape controllers 1 and 2, and the magnetic tape controllers 1 and 2 are connected to a host system 3 and interconnected. I have. Further, the magnetic tape controllers 1 and 2 include a plurality of magnetic tape devices 4 and 5.
(In FIG. 1, two magnetic tape devices are shown, but three or more magnetic tape devices may be connected to the magnetic tape controllers 1 and 2.) Then, referring to FIG. 2, the magnetic tape controllers 1 and 2
Have similar components. Therefore, the magnetic tape control device 1 will be described here. The magnetic tape control device 1 includes a channel connection unit 101, and is connected to the host system 3 by the channel connection unit 101. The magnetic tape control device 1 includes a data buffer 102, a drive control unit 103, and a data compression unit 104. Block combining section 105 performs blocking for connecting logical blocks, and block separating section 106 deblocks blocking data in data buffer 102. The data decompression unit 107 performs data decompression. The selection circuit 108 selects one of the compressed data path and the uncompressed data path, and
In step 09, one of the blocking data and non-blocking data is selected, and in the selection circuit 110, one of the deblocking data and non-deblocking data is selected. The selection circuit 111 selects one of the decompressed data and the non-decompressed data. The microprocessor 112 decodes commands received from the host system 3 and executes control according to each command. The control memory 113 has a microprocessor 112
Are stored.

Referring to FIGS. 1 and 2, a write process using a data compression and auto-blocking mechanism will be described. When the data compression and auto-blocking operation mode (hereinafter referred to as a specified operation mode) is specified by the mode specification command sent from the host system 3, the microprocessor 112 stores the specified operation mode in the control memory 113. Subsequently, when the microprocessor 112 decodes the write command sent from the host system 3, the selection circuits 108 and 109 select data compression and blocking, respectively.

Next, the plurality of logical data blocks sent from the host system 3 are stored in the data buffer unit 102 through the data compression unit 104 and the block synthesis unit 105 in the format shown in FIG.

In FIG. 3, a data buffer 102 stores a plurality of physical data blocks. The physical data blocks 200 and 300 respectively include format information 201
, And 301 and a plurality of logical blocks 202 and 302. The format information 201 and 301 is an area for storing information on each block, and indicates whether the format is a standard format or an extended format (the presence or absence of blocking and the number of logical blocks). Is shown. Here, a plurality of logical data blocks 202 are stored in the extended format.
And 302 are connected. The blocks are connected by the logical blocks 202 and 302.
Is performed within a range not exceeding a certain capacity.

When a predetermined amount or more of data is stored in the data buffer unit 102, the microprocessor 112 starts writing to the magnetic tape device 4 via the drive control unit 103. The write operation from the data buffer 102 to the magnetic tape device 4 is performed between the host system 3 and the data buffer 102 asynchronously with the data transfer, and can operate simultaneously. If an error is detected during the write operation from the data buffer 102 to the magnetic tape device 4, the microprocessor 112 abnormally ends the write command sent from the host system 3 or the command issued next, and outputs error information and data. The presence / absence of unwritten data in the buffer 102 is reported to the host system 3. The host system 3 determines that retry should be performed via another magnetic tape controller 2 based on the error information, and determines that unwritten data remains in the data buffer 102 of the magnetic tape controller 1. Then, the extended read buffer command is continuously transferred to the magnetic tape controller 1 until all the physical data blocks in the data buffer 102 have been transferred.

When the microprocessor 112 of the magnetic tape controller 1 receives the above-described extended read buffer command, the microprocessor 112 converts the data shown in FIG. 3 into a plurality of logical blocks connected in physical block units (area units indicated by 200 and 300). Forward. At this time, the microprocessor 112 sets the selection circuits 110 and 111 of the magnetic tape control device 1 to select non-deblocking and non-decompression, respectively. As a result, when all the data in the data bag 102 has been transferred to the host system 3, no data larger than the capacity of the data buffer 102 has been transferred.

The host system 3 transfers the collected data from the magnetic tape controller 1 to the magnetic tape controller 2 as described above.
Is re-transferred using an extended write buffer instruction in physical block units. Upon receiving the extended write buffer command, the microprocessor 112 of the magnetic tape controller 2 sets the selection circuits 108 and 109 to select non-compression and non-blocking, respectively, and starts data transfer. Therefore, the transmitted data is stored in the data buffer 102 of the magnetic tape control device 2 in the same manner as in the data buffer 102 of the magnetic tape control device 1.

When the restoring of all the collected data is completed, the host system 3 resumes the suspended original processing, and the data finally restored in the magnetic tape controller 2 is written on the magnetic tape. Will be.

[0022]

As described above, according to the present invention, in order to perform recovery processing for a failure, when transferring the compressed data in the data buffer to the higher-level device, the data is transferred without decompression, and the data buffer is again transferred. When the data is restored, the compressed data is transferred as it is, so that the host system does not need to secure a data storage area larger than the physical capacity of the data buffer when collecting the data in the data buffer. Also,
Since a plurality of data blocks are transferred together, there is an effect that the time required for collecting and restoring data can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a subsystem according to the present invention.

FIG. 2 is a block diagram showing the magnetic tape control device shown in FIG. 1 in detail.

FIG. 3 is a diagram schematically showing a data storage state of a data buffer shown in FIG. 2;

FIG. 4 is a diagram showing data blocks on a magnetic tape for explaining auto-blocking.

[Explanation of symbols]

1, magnetic tape control device 3 host system 4, 5 magnetic tape device 101 channel connection unit 102 data buffer 103 drive control unit 104 data compression unit 105 block synthesis unit 106 block separation unit 107 data decompression unit 108, 109, 110, 111 Selection circuit 112 Macro processor 113 Control memory 200, 300 Physical data block 201, 301 Format information 201, 302 Logical data block 401, 402, 403, 404, 405, 406
Blocks on tape 407, 408, 409, 410, 411, 412
Logical data block

Claims (2)

(57) [Claims] A peripheral device control device, which is located between an external storage device and a host device and controls data transfer between the host device and the external storage device, includes a data buffer and data from the host device. First storing means for storing compressed data in the data buffer; and first storing means for transmitting the compressed data as first transfer data to the external storage device asynchronously with a write operation to the data buffer.
Transfer means for transferring compressed data in the data buffer in a compressed state as second transfer data to the higher-level device in response to a request from the higher-level device; Storing the second transfer data in the data buffer as compressed data.
Peripheral device control device, comprising: 2. A peripheral device control device, which is located between an external storage device and a higher-level device and controls data transfer between the higher-level device and the external storage device, includes a data buffer and a data buffer transmitted from the higher-level device. First storage means for combining a plurality of logical data blocks into one data block and storing the combined data block in the data buffer, and first transfer of the combined data block asynchronously with a write operation to the data buffer First transfer means for sending data as data to the external storage device, and, when the write processing is abnormally interrupted, the synthesized data block in the data buffer as second transfer data in response to a request from the higher-level device. Transfer means for transferring the second transfer data transferred again from the higher-level device to a synthesized data block. And a second storage means for storing the data in the data buffer.