JPS62256266A - Magnetic disk control device - Google Patents

Abstract

PURPOSE:To decrease a turn around time by reporting the end to a host device by the end of write to a write data storage means and to one magnetic disk with respect to a write command from the host device to a double write object device. CONSTITUTION:When a data processing unit 2 decides a double write pair and issues a command to a magnetic disk control device 4, the device 4 stores the relation of correspondence of master/slave magnetic disk devices 61, 62 being the object to double write to a device correspondence table TB 441. When the unit 2 applies a write command to the device 61, the device 4 receives the write command through an interface IF section 41, a control section 44 uses the device number of write command to search the TB 441 thereby recognizing a double write device and track control information is read from a track control TB 442. The control section 44 uses the control information to store a write data in a storage section 45 and writes the data in a master device 61 through a write/read section 42 and an IF section 43 to apply a write end report to the device 2. Then the write data stored in a storage section 5 is written in a slave device.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic disk control device having a function of double writing the same data to two magnetic disk devices, and in particular, to reduce turnaround time. This invention relates to a double write control method.

Conventional technology Conventionally, as a technology to improve data reliability by writing the same data twice using magnetic disk drives, an operating system (hereinafter referred to as O3) is used for two magnetic disk drives. Generally, a method has been adopted in which each write command is issued separately and the operation is terminated after waiting for the completion of both commands.

In addition, as a method in which the magnetic disk control device performs double writing using two subordinate magnetic disk devices, write data received from the data processing device is written to one of the magnetic disk devices at the same time. A method aimed at shortening the turnaround time has also been proposed, in which the information is stored, and after completion of both operations is reported to the data processing device, data is written to the other magnetic disk device during the idle time of the magnetic disk control device. ing. However, due to the ease of control of double writing using conventional magnetic disk control devices, after the write completion is reported to the data processing device, a write command is issued again before writing data in the storage section to the other magnetic disk device. When issued, the command is kept in a waiting state even if the writing track is different.

Problems to be Solved by the Invention In the double writing method using O5 mentioned above, it is necessary to execute the same command twice, so the C
In addition to deteriorating the performance of the PU, since the operation is completed only after writing to both magnetic disk devices is completed, there is a drawback that the performance of the access time is decreased, that is, the turnaround time is extended.

In addition, in the double write method using the magnetic disk control device described above, since double write control is performed for each magnetic disk device, turnaround time cannot be improved in a system where access is concentrated on one device. was there.

The present invention has been made in view of the above-mentioned conventional circumstances, and
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a novel magnetic disk control device that eliminates the notation defects inherent in the prior art.

Means for Solving the Problems In order to achieve the above object, the magnetic disk control device according to the present invention includes: device correspondence table storage means for storing the correspondence of 'A jfl to be double-written; It has write data storage means for storing write data for overwriting, and track control table storage means for performing double writing control on a track-by-track basis, -! In response to a write command from the first device to the target device for dual writing, upon completion of writing to one magnetic disk device and writing to the write data storage means, a completion report is made to the device in second place. It is characterized by

Embodiment Next, a preferred embodiment of the present invention will be specifically explained with reference to the drawings.

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

Referring to FIG. 1, a magnetic disk control device 4 according to the present invention is connected to a data processing device 2.
an interface unit 4 which performs input/output with the interface unit 4; a write/read unit 42 which is connected to the interface unit 41 and the interface unit 43 and controls data writing/reading; and a magnetic disk unit 6 which is connected to the magnetic disk unit 6. an interface section 43 that performs input/output to and from the interface section 4;
1 and the writing/reading section 42 and storing write data for double writing; the interface section 4; the writing/reading section 42; the interface section 43; and the storage section 45 It is connected to perform overall control and 2
A control unit 44 that performs double writing control by holding a device correspondence table 441 that stores the compatibility status and device status of the device that is the target of overwriting, and a track control table 442 that performs double writing control on a track-by-track basis. It consists of

First, the operation of the magnetic disk control device 4 when reading data from a magnetic disk device that is not subject to double writing is similar to that of a conventional magnetic disk control device and is well known, so a description thereof will be omitted.

Next, the correspondence between the magnetic disk devices g to be subjected to dual writing is determined by managing the magnetic disk devices 6 at the O8 operating in the data processing device 2 and determining a double weight pair. When necessary, such as when the magnetic disk controller 4 is turned on or when the magnetic disk controller 4 is powered on, the physical information held by all the connected magnetic disk devices (jumper packages, etc.) is sent to the magnetic disk controller 4. ) may be recognized by reading it. In either case, the magnetic disk control device 4 stores the correspondence of the magnetic disk devices subject to double writing in the device correspondence table 441, and also stores the device status in the reading device correspondence table 441 using a known method.

The contents of the device correspondence table 441 are shown in FIG. The device status information when the power is turned off is valid if there is no abnormality in the magnetic disk device.

Double write control of the magnetic disk controller 4 will be described below.

It operates on the data processing device 2. s is a magnetic disk g M
When a write command is executed for B
4 receives the device number, write command, and operation track information. When the control unit 44 searches the device H' correspondence table based on the device number and recognizes that it is a dual write device, the control unit 44 selects the primary magnetic disk device 81 and the sub magnetic disk device 62.
Check the device status and operate as follows according to the ζ setting status.

First, when either the primary device 61 or the secondary device 62 is in a disconnected state, conventional single write processing is executed on a valid magnetic disk device, and after the operation is completed, a completion report is sent to the data processing device 2.

When both the primary device 61 and the secondary device 62 are valid, the control unit 44 updates the track control table 442 based on the specified operation target l/rack information and the track control pointer information stored in the device correspondence table. Read track control information. Track control information is 1 per track
When the bit information is "IIQ1", it indicates that writing to the track is possible, and when it is "1", it indicates that the track is waiting for double writing.

As shown in FIG. 3, the read control of the track control information in the track control table 442 is performed so that the track control table pointer indicates the deviation for each device. Since this shows the deviation, it is possible to do this by reading out one bit of the memory address generated from the image information.

The control unit 44 determines that the read track control information is “0′”.
At this time, the magnetic disk device 61 is selected through the interface unit 43 and a seek operation to the target track is instructed. Thereafter, the control section 44 can receive the write data by instructing the data processing device 2 to transmit the write data through the interface section 41, so that the received data can be stored in the storage section 45 and written at the same time. Data is written to the magnetic disk device 61 through the read/write section 42 and the interface section 43.

When the write operation to the primary device 61 and the storage unit 45 is completed normally without error, the control unit 44 notifies the data processing device 2 of the completion of the write command, and also updates the corresponding track information in the track control table to il 111. In other words, the state is changed to a double write wait state.

Further, when the read track control information is "1", the corresponding track is in a double write waiting state, so the control unit 44
After once storing the write command requested by the data processing device 2 and completing the write operation for the relevant trunk of the sub-device 62 using the write data already stored in the storage unit 45, the write command requested by the data processing device 2 is completed. Execution control of the written write command is performed as described above.

Note that the storage unit 45 stores write data of all tracks waiting for double writing.

After completing each command operation, the magnetic disk control device 4 checks whether there is an input/output request from the data processing device 2. If there is no input/output request, the magnetic disk control device 4 sequentially reads the track control information from the track control table and waits for double writing. Check for status tracks.

If there is a track waiting for double writing, the device number and track address are obtained by reverse conversion from the read address, and the corresponding write data in the storage unit 45 is used to write to the corresponding sub magnetic disk device. When the write operation is completed normally, the track control information in the track control table is changed to "0" (writable), and at the same time, the write data recording area ↑a of the storage unit 45 is released as a vacant state.

Data processing H1Fff is performed with the following two operations as one cycle.
If an address state with no request occurs in checking whether there is an input/output request from i2, the above operation cycle is repeated until there are no tracks waiting for double writing.

According to the above explanation, since the magnetic disk control device 4 is capable of double writing control for each track based on the track control information in the track control table 442, the storage unit 45 is stored in the secondary magnetic disk device after writing to the primary magnetic disk device is completed.
It is clear that even if a write command is requested again before data is written, the waiting state will not occur if the conditions are different.

Note that the read operation for the 2M write target device is performed only when the primary magnetic disk device 61 is used even if both magnetic disk devices are enabled.
However, since it is not directly related to the present invention, it will not be described.

As described in detail, according to the magnetic disk control Rrf of the present invention, it is possible to realize double writing in a magnetic disk device with a short turnaround time without disturbing the O8.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a magnetic disk control device according to the present invention, FIG. 2 is a diagram showing the contents of the device correspondence table shown in FIG. 1, and FIG. 3 is a track control table shown in FIG. 1. FIG. 216. data processing device, 4. , , magnetic disk control device, 6. ,,magnetic disk device, 4114391. Interface section, 42. , , write-read unit, 44,
, ,control unit, 45.6. Storage section, 441, , ,
Device correspondence table, 442. ,,) Rank control table, fil, , , Primary magnetic disk device for dual writing, 62, , , Secondary magnetic disk device for dual writing Patent applicant NEC Corporation Representative Patent attorney Yutabe Kumagai Figure 1

Claims (1)

[Scope of Claims] A magnetic disk control device that controls writing and reading of a magnetic disk device, comprising: device correspondence table storage means for storing a correspondence relationship between devices subject to double writing; It has write data storage means for storing write data, and track control table storage means for performing double write control on a track-by-track basis. On the other hand, a magnetic disk control device is characterized in that a completion report is sent to a host device upon completion of writing to one of the magnetic disk devices and writing to the write data storage means.