JPS61250720A - Magnetic disc controller - Google Patents

Abstract

PURPOSE:To attain rising of a duplicated system at power failure restoration automatically, safely and surely by providing a state holding section to a mag netic disc controller. CONSTITUTION:A state holding section 24 has a means such as a latch relay or nonvolatile storage and holds the just preceding state even when power interruption takes place. When a magnetic disc device 4 is disconnected from the system and operated singly as the magnetic disc controller 3 and a magnetic disc device 5, the state holding section of a controller 2 holds the 'disconnecting' state as an information bit and the state holding section of the controller 3 holds the state of 'master system'. If power failure takes place in this state and then the power failure is restored, a CPU 1 reads the content of each state holding section of magnetic disc controllers 2, 3 and uses the system holding the master system as the main system again depending on the content and raises the disc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magnetic disk control device in a computer system having dual magnetic disk devices.

[Technical background of the invention]

An example of the configuration of a system having dual magnetic disk drives is shown in FIG. In Fig. 3, (1) is a central processing control unit I (hereinafter abbreviated as CPU), (2
)(3) is a magnetic disk control device, and (4) and (5) are magnetic disk devices. Conventionally, the above-mentioned magnetic disk control devices (2) and (3) have been controlled only by the magnetic disk device itself. ! (4) Regardless of whether or not (5) is duplicated as in 1 in Figure 3, it is exclusively used for CP.
Its main function was to control data transfer between the U and the magnetic disk.

[Problems with background technology]

In a system having the magnetic disk control devices (2) and (3) as described above and configured as shown in FIG.

(4) If a failure such as a power outage occurs while the system is operating only with the other magnetic disk unit due to a failure in one of the magnetic disk units listed in (5), and the system is temporarily stopped, the system will restart automatically. Even if you try to start up,
The state immediately before the above system stops (disk connection state)
is not maintained, so there is a drawback that it is impossible to return to the previous state. This is because if the cause of the failure in the magnetic disk device that occurred immediately before a power outage was not due to a physical failure of the magnetic disk but to a logical failure of the file on the magnetic disk device, this detection is performed by the hardware. This is because there is a possibility that the failed magnetic disk device, which was the original main system, may be selected as the main system.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to enable a duplex magnetic disk drive to be started up after a power failure, returning to the state immediately before the power failure.

[Summary of the invention]

The present invention provides a magnetic disk control device with a state holding section that exchanges information with the control section and has means such as a latch type relay or non-volatile memory, and the CPU reads this out at startup. This makes it possible to achieve the above objectives.

[Embodiments of the invention]

FIG. 1 is a block diagram showing the internal configuration of an embodiment of the present invention. In Fig. 1, (21) is a CPU interface, (22) is a control unit, (23) is a magnetic disk device (including a drive unit) interface, and (24) is a state holding unit, which is a latch type relay or non-volatile memory. This is a part that maintains the state immediately before the power is cut off even if the power is cut off. (25) is the write/read data to the magnetic disk device, (26) to (30) are (21)
) to (24) respectively.

Next, the operation will be explained. - In Figure 3 showing the membrane configuration,
Magnetic disk control device (2) and magnetic disk device (4)
Assuming that the part consisting of the above is the main system, and the part consisting of the magnetic disk control unit (3) and the magnetic disk unit (5) is the slave system, writing of data from the CPU (1) to each unit is normally done by the main system. , and the slave system, and reading to the CPU (1) is performed only from the main system. This normal operation is performed by the CPυ interface section (21) in the control device shown in Figure 1.
This is performed under the control of the control section (22) via the magnetic disk interface section (23). Control unit (24)
((242) or (243)) holds an information bit indicating whether it is the main system or the slave system.

This information can be written (updated) or read only by a request from the CPU (1), and even if the power supply to this control device is cut off, this information bit state is maintained.

A failure occurred in the magnetic disk drive (4) of younger brother 3, so the magnetic disk drive (4) was disconnected from the system.
Magnetic disk control device (3) and magnetic disk device (5)
If the operation is performed as a standalone system (main system only), the state holding unit (242) of the control device (2) holds the "disconnected" state as an information bit, and the state of the magnetic disk control device (3) The holding unit (243) holds the "main system" state.

If a power outage occurs in this state and then the power is restored, the CPU (1) will be replaced by the magnetic disk controller (
2) and (3), the state holding unit (242) (24
3) The information bits held in the above information bits are read out.

Depending on the contents, the disk is started up again with the system holding the main system as the main system.

The second flowchart summarizes the operations during power outage recovery.
It is a diagram.

Although the magnetic disk control device has been described above, the present invention is applicable not only to this device but also to external storage devices such as magnetic drums.

〔Effect of the invention〕

The present invention is as described above, and has the effect of automatically and safely and reliably starting up a duplex system upon recovery from a power outage.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the internal configuration of an embodiment of the present invention, Fig. 2 is a flowchart of one operation when recovering from a power outage, and Fig. 3 is an example of the configuration of a system with dual magnetic disk drives. FIG. 1: Central processing control unit, 2.3: Magnetic disk device, 4.5: Magnetic disk device, 21.23: Interface. 22: Control unit, 24: State holding unit.

Claims (1)

[Claims] A control unit interposed between the central processing control unit and the magnetic disk control unit, a state holding unit of the control unit, and each interface interposed between the control unit and the central processing control unit and the magnetic disk unit. A magnetic disk control device comprising: