JPS6095663A - Automatic switching device of dual type magnetic disk device - Google Patents

Abstract

PURPOSE:To detect at an early stage a read failure of a magnetic disk device of a slave system, and to reduce an all-out stop of the magnetic disk device by switching periodically the magnetic disk device of a master system and the magnetic disk device of the slave system. CONSTITUTION:When an input/output event to magnetic disk devices Vo-Vn is generated in a CPU6, the CPU6 starts a dual type disk monitor module 5. The CPU6 executes an input and an output to the magnetic disk device of a specified line, and thereafter, in case when it is ended normally, the dual type disk monitor module 5 switches the master system magnetic disk device of its specified line and a slave system magnetic disk device. Also, a clock module 3 starts the dual type disk monitor module 5 at a designated time asynchronously with said processing, and the master system magnetic disk deive of said line in the course of a dual operation and the slave system magnetic disk device are switched periodically.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an automatic switching device for a duplex magnetic disk drive used in a computer system having a duplex magnetic disk drive.

[Technical background of the invention and its problems]

2. Description of the Related Art Conventionally, as a method for preventing a system from stopping due to a failure in a magnetic disk device, a dual configuration of a master disk system and a slave disk system has been adopted for magnetic disk devices. In a magnetic disk drive with such a redundant configuration, system reliability can be improved by logically separating the failed magnetic disk drive from installation A and allowing the normal magnetic disk drive to operate as the master disk. This was to improve operating rates.

By the way, in this duplex configuration, in order to minimize the deterioration in system performance due to duplication, normally only writing is duplexed, and reading is performed using only the mask disk system. As a result, only writing is performed on the slave-type magnetic disk device, and even if a failure occurs in the slave-type magnetic disk device that causes a read failure, it is impossible to detect it. there were.

Therefore, if a failure occurs in the mask type magnetic disk unit while the slave type magnetic disk unit is experiencing a read failure, both the mask and slave type magnetic disk units will fail. However, there was a drawback that the system could not continue to operate.

[Help for invention]

In view of the above-mentioned drawbacks, an object of the present invention is to provide a duplex magnetic disk device that detects read failures in slave magnetic disk devices at an early stage and reduces total stoppage of both mask and slave magnetic disk devices. An object of the present invention is to provide an automatic switching device.

[Summary of the invention]

In the present invention, for each duplex magnetic disk device,
a line control register that holds switching information such as when duplication is in operation, during input/output, and when waiting for switching between master disk and slave disk; and a master/slave switching module that switches between master disk and slave disk based on the switching information. , an input/output status register that holds the line number and status of the first magnetic disk device that performed input/output, setting and canceling switching control information of the line control register, and inputting the line number and status to the input/output status register. The dual disk monitoring module is equipped with a duplex disk monitoring module that starts the mask/slave switching module after setting, and a clock module that starts the master/slave switching module at a preset specified time. In addition to switching the mask disk and slave disk of a pair of magnetic disk drives whose output has ended normally, when activated by the clock module, the mask disk and slave disk of all magnetic disk drives in duplex operation are switched. By periodically switching between the two, the above objective is achieved.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an automatic switching device for a duplex magnetic disk drive according to the present invention will be described below with reference to the drawings. Figure 1 shows the second aspect of the present invention.
1 is a block diagram showing an embodiment of a dual magnetic disk device; FIG. The automatic switching device 100 for a duplex magnetic disk device includes a line control register (LRG) that holds the unit number of the magnetic disk device constituting the duplex and switching control information for controlling switching between a master disk and a slave disk.
)1, and the master unit number and slave of this LRG1.
A master/slave switching module (MS, C) 2 that switches between a mask disk and a slave disk by exchanging unit numbers, and a clock module (TM) 3 that generates an interrupt to the MSC 2 at a specified time!
:, input/output near] status register (SRG) 4 and r
, setting and canceling the input/output flag of Rc 1 and 5RG4
and a dual disk monitoring module (DMG) 5 that performs settings and starts the MSC 2.

The duplex magnetic disk system 200 includes a central processing unit (
CPU), 6, magnetic disk controller (DSCI)
) Magnetic disk device group Vo+V connected via 7
s+ ---vn-1, and a group of magnetic disk devices V□+Vs, ---Vn connected to the CPU 6 via a magnetic disk controller (DSC2) 8. A set of magnetic disk drives constituting duplication is called a line, and in the example shown in FIG.
. and Vl constitute line 0, V2 and V constitute line 1, and Vn-1 and Vn constitute line m. or,
The magnetic disk devices constituting each line are the same and can be used as either a mask system or a slave system. For example, in line O, if the magnetic disk device ■ becomes the master disk (sometimes called a master unit), the magnetic disk device Vl becomes a scrap disk (sometimes called a slave unit ψ). Therefore, Switching between the master disk and slave disk means, in the above example, switching the magnetic disk device Vo to the slave disk and switching the magnetic disk device Vo to the slave disk.
1 as a mask disk. Furthermore, the magnetic disk device serving as a slave disk only performs writing, and only writing is duplicated.

Figure 2 shows the line control register (LRG) shown in Figure 1.
This shows the contents of 1. That is, the following items are held for each line of a set of magnetic disk drives that constitute a duplex. The mask unit number 9 indicates the unit number (physical device address) of the magnetic disk device that performs both reading and writing, and the slave unit number 101 indicates the unit number of the magnetic disk device that only writes. The duplex operation flag 11 indicates that the data is being read from the master disk or is being written to the mask disk and slave disk (double writing), and the input/output flag 12 indicates that the data is being input/output. This is a switching wait flag 13 indicating that the switching of the master unit number and slave unit number is pending with input/output completion 1. As described above, the t'ft information of the duplex operation flag 11, the input/output flag 12, and the switching wait flag 13 are collectively referred to as switching control information.

The input/output status register (sItG) 4 holds the number of the line that is the target of input/output, and three types of status: normal end, master unit failure, and slave unit failure.

Next, the operation of this embodiment will be explained. When an input/output event to the magnetic disk device occurs in the CPU 6, the CPU
U6 starts the duplex disk monitoring module (DMG) 5. The duplex disk monitoring module 5 receives the number of the line to be input/output from the CPU 6 as information at the time of startup, and after turning on the input/output flag for the line in the line control register (LRG) 1, the line The relevant line information in the control register 1 is returned to the CPU 6.

The CPU 6 performs input/output to the magnetic disk device based on this duplex configuration information, but since the input/output management method in the duplex configuration is already a known fact, the explanation thereof will be omitted here.

On the other hand, when the input/output to the magnetic disk device is completed, the CP
U6 starts up the duplex disk monitoring module 5 again. The duplex disk monitoring module 5 receives the input/output results, that is, the line number and status from the CPU 6, sets these in the input/output status register (SRG) 4, and then starts the master/slave switching module (MSC) 2. Furthermore, the completion is notified to the CPU 6. The master/slave switching module 2 is the duplex disk monitoring module 5.
When activated, one of the following operations is performed according to the status set in the input/output status register 4. (1) In the case of normal termination, if the switching wait flag 13 of the line control register 1 is on, the master unit number and slave unit number of the line are swapped. That is, the mask disk and slave disk are switched. (2
) If there is a failure in the master unit, turn off the redundant operation flag 11 of the line control register 1 and exchange the master unit number and slave unit number. Here, a normal magnetic disk device is assumed to be a master disk. (
3) If there is a failure in the slave unit, turn 7 lag 11 of the line control register 1 during duplex operation to OFF. When the master/slave switching module 2 completes any of the above operations, it turns off the switching wait flag 1.3 of the line control register 1 and initializes the input/output status register 4.

The duplex magnetic disk automatic switching device 100 performs the following operations asynchronously to the above operations. That is, the clock module (TM) 3 activates the master/slave switching module 2 at a specified time set in advance. When the master/slave switching module 2 receives activation from the clock module 3, it executes the following operation corresponding to the switching information of the line control register 1 on all lines of the line control register. (1) When the input/output 7 lag 12 is on, the switching wait flag 13 of the line is turned on. (2) If the input/output flag 12 is off and the redundant operation flag 11 is on, the master unit number and slave unit number of the line are swapped. That is, here, switching is performed between the mask type magnetic disk device and the slave type magnetic disk device. (3) If the 7 lug 11 is off during duplex operation, nothing is done to the line. Note that the contents of the line control register 1 can be arbitrarily initialized by the CPU 6 via the duplex disk monitoring module 5.

According to this embodiment, when the CPU 6 inputs/outputs input/output to a magnetic disk device of a specific line and ends normally, the duplex disk monitoring module 2 controls the mask-based magnetic disk device and the slave-based magnetic disk device of the line. At the same time, the clock module 5 activates the duplex disk monitoring module 2 at a specified time asynchronously with this, and the clock module 5 starts the duplex disk monitoring module 2 to monitor the mask magnetic disk device and slave magnetic disk of the previous line that are in duplex operation. By periodically switching the devices, read failures in both the mask and slave magnetic disk drives can be equally detected, which means read failures in the slave magnetic disk drive can be detected early, and the mask system magnetic In the event of a disk device failure, it is possible to reduce the total system stoppage due to reading errors in the slave magnetic disk device, and furthermore, it is possible to improve the operating rate of the system by -1. In the past, during repair work, etc., switching between the mask type magnetic disk device Ff and the slave type magnetic disk device was done manually, but in this embodiment, this is done automatically, so such repair work is easy. There is no need for this at all, resulting in labor savings.

〔Effect of the invention〕

As described above, according to the automatic switching device for a duplex magnetic disk device of the present invention, by periodically switching between the mask type magnetic disk device and the slave type magnetic disk, f disk device, the slave type magnetic disk This has the effect of detecting reading failures in the device at an early stage and reducing total stoppage of both mask and slave magnetic disk devices.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an automatic switching device for a duplex magnetic disk drive of the present invention, and FIG. 2 is a diagram showing an example of the contents of the line control register shown in FIG. 1. 1... Line control register (LRG) 2... Master/slave switching module (MSC) 3... Clock module (TM) 4... Input/output status register (SRG) 5...
Duplex disk monitoring module (DMG) 6...Central processing unit (CPU) 100...Automatic switching device 200 for magnetic disk device.
...Duplicated magnetic disk system V, -Vn...Magnetic disk device representative patent attorney Noriyuki Noriyuki (and one other person)

Claims (1)

[Claims] Each duplicated magnetic disk device has a line control register that holds switching information such as when duplication is in operation, during input/output, and when waiting for switching between the master disk and slave disk, and a line control register that stores the switching information. a master/slave switching module that switches between a master disk and a slave disk based on the input/output, an input/output status register that holds the line number and status of a pair of magnetic disk devices that have performed input/output, and switching control information in the line control register. a duplex disk monitoring module that activates a master/slave switching module after setting and canceling the setting and setting the line number and status to the input/output status register;
The duplex disk monitoring module includes a clock module that starts the master/slave switching module at a preset specified time, and the duplex disk monitoring module detects the master disk and slave disk of the first magnetic disk device whose input/output has been successfully completed. In addition to switching, the duplex magnetic disk device is characterized in that, when reverse activated by the clock module, the master disk and slave disk of all the magnetic disk devices in duplex operation are periodically switched. Automatic switching device.