JPH01102658A - File write back-up system - Google Patents

Abstract

PURPOSE:To prevent the destruction of a file caused by a service interruption occurring in a data writing mode by backing up a memory via a spare power supply and adding a flag circuit to detect the service interruption occurring in the data writing mode so that the data is rewritten at recovery of the service interruption and only when said flag is set based on the stored write data. CONSTITUTION:An under-write service interruption detecting flag circuit 2-2 which detects a service interruption in a write mode and sets a flag is added to a disk controller 2 together with a battery 2-5 which supplies the power to the circuit 2-2 and a control data memory circuit 2-1 at service interruption. When the service interruption is recovered, a microprocessor 2-3 identifies the flag and performs the write processing again by a battery 2-5 based on the stored control information and data only when the flag is set. In such a way, the data can be correctly written again at recovery of the service interruption that occurs while the data is written to a disk device 3. Thus a serious fault of a system is never produced while a file is kept broken.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a disk control device, and particularly to a file write backup method suitable for preventing file destruction due to a power outage during data writing.

[Conventional technology]

In conventional devices, the entire main device is backed up by a battery as described in Japanese Patent Application Laid-open No. 61-18319, and the larger the device, the more expensive the backup equipment becomes.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology has a problem in that it is very expensive in terms of cost and does not take into consideration low-cost small computer systems.

An object of the present invention is to provide a low-cost and simple file backup method that solves the above cost problem.

[Means for solving problems]

The above purpose is to back up the memory that temporarily stores the write data and its control information that are busy in the disk control device with a backup power source, and to provide a flag circuit for detecting a power failure during writing, so that the control unit can detect the power failure when the power is restored. This is achieved by identifying the flag and rewriting with the stored write data only when the flag is set.

[Effect]

The latest control information and data during the write operation are stored in the memory (control data storage circuit).

The power failure detection flag circuit during writing operates only when a power failure occurs while the write circuit is in operation, and the detection flag is set.

Both the control data storage circuit and the power failure detection flag circuit during writing are backed up by a backup power supply.
The memory contents will not be erased even if there is a power outage.

After the power is restored, the control unit identifies the flag and performs rewriting processing using the control information and data stored in the standby power supply only if the flag is set.
Power off (“FIi”) except during normal operation and writing
(by turning off the L source switch, power outage, etc.), the rewriting operation will not be performed by mistake.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, 1 is a processing device, 2 is a disk control device, and 3 is a disk device. Data is written to the disk device 3 using a disk address for disk control transferred from the main memory IJ 1-1 to the control data storage circuit 2-1 via the input/output bus α.

Based on control parameters such as the number of data and write data, the write control circuit 2-4 operates under the control of a microprogram executed by the microprocessor 2-3 that functions as a control unit, and the write control circuit 2-4 operates via the disk interface e. Write designation and data writing to the disk device 3 are executed.

The disk control device 2 is provided with a write power failure detection flag circuit 2-2 that detects a power failure during writing and sets a flag.
A power reset signal f sent via the input/output bus a when the power is turned off from 2-4 and a writing signal C sent from the write control circuit 2-4 are input from 2-4. The circuit is configured such that only during writing, the power failure detection flag signal d is output to the microprocessor 2-3. Further, the battery 2-5 is connected to the control data storage circuit 2-1 and the write power failure detection circuit 2-2 through a power supply line.

It supplies power during power outages and serves as a backup power source to prevent information in the circuit from disappearing.

Figure 2 is a flowchart explaining the behavior of the hardware and microprogram after the power is restored and the power is cut off due to a power outage during writing. In the figure, there is a power outage while the hardware is performing a write operation, and the write power failure detection flag is set in accordance with the explanation with reference to FIG. 1 above.

After the power is restored, the microprogram performs initialization processing such as initial diagnosis, and outputs the power failure detection flag signal '? :a
As a result of the separation, writing activation and control are performed again using the control parameters and data held in the control data storage circuit 2-1.

As described above, according to this embodiment, even if there is a power failure during a write operation, data can be written correctly after power is restored.

〔Effect of the invention〕

According to the present invention, by adding a simple circuit, it is possible to prevent a power outage during a write operation to a disk device.

Since it is rewritten correctly when power is restored, it is possible to solve problems that cause serious system failures when files are corrupted.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a hardware block diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing the flow of operations in FIG. 1. 1... Processing device. 1-2...Power reset circuit, 2...Disk control device. 2-1... Control data storage circuit. 2-2... Power failure detection flag circuit during writing. 2-3...Microprocessor. 2-4...Write control circuit. 2-5...Battery, b...Battery power supply line, C...Writing signal. d... Power outage detection flag signal during writing. f...Power reset signal. Inspection 2 Z

Claims (1)

[Claims] 1. Storage means for temporarily storing write data and control information for the disk device; a data write circuit that reads write data from the storage means and writes it to the disk device; and a control means for controlling the data write operation. A power outage flag circuit during data writing detects that the data writing circuit is in the process of writing data and there is a power outage, and stores the state; and a means for supplying power, and when the power is restored, the control means rewrites the write data according to the contents of the storage means if the flag circuit has stored the state. Write backup method.