JPH08235078A - Magnetic disk device provided with backup function - Google Patents

Abstract

PURPOSE: To turn off the power source of a magnetic disk device having a write cache even at the time of executing the write cache. CONSTITUTION: This magnetic disk device with write cache (HDD) is provided with an operation monitoring part 3 controlling the data of a cache and monitoring the processing of a cache 5 and a magnetic disk medium 9 and a backup function part 6 holding the data of the cache 5 and the data of the operation monitoring part 3 when the power source of the HDD is turned off. The operation monitoring part 3 monitors the address of the data written in the cache 5. As a result, the power source of the HDD can be turned off at any time and data can normally be written in the HDD even at the time of a sudden power failure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device with a backup function, and more particularly to a write cache (Wri
te Cache).

[0002]

2. Description of the Related Art Conventionally, a magnetic disk device having a write cache does not have a backup function. Therefore, during write cache operation, the power of the magnetic disk device is turned off until all cache data is written to the magnetic disk medium. could not.

[0003]

In the above-mentioned conventional magnetic disk device, the main body recognizes that the writing has been completed in the magnetic disk device when the data is sent to the cache during the write cache operation. Since the time to write data from the cache to the magnetic disk medium is longer than the time to write data from the cache to the cache, writing to the magnetic disk device will end if all the cache data is not actually transferred to the magnetic disk medium. Not not.

Therefore, if the power of the magnetic disk device is turned off before all the data in the cache is transferred to the magnetic disk medium, the remaining data in the cache is erased and the data transfer is completed in the main body. Even if it is recognized, it will not be correctly transferred to the magnetic disk medium.

[0005]

According to the present invention, in a magnetic disk device with a write cache, data sent from a higher-level device via an interface is monitored and the last data is written in the cache. An operation monitoring unit that holds address information and monitors data written in the magnetic disk medium from the cache, and a cache data and data of the operation monitoring unit when the magnetic disk device is powered off. And a backup power supply for holding the same.

[0006]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. In this embodiment, as shown in FIG. 1, a face 2, a cache 5 and a magnetic disk medium 9 and an interface for controlling them respectively. Face control unit 1, memory control unit 4 and head / medium control unit 8, operation monitoring unit 3 for monitoring the operations of interface control unit 1 and memory control unit 4, interface control unit 1, operation monitoring unit 3, The magnetic disk device configured to include the CPU 7 that controls the operations of the memory control unit 4 and the head / medium control unit 8 backs up the operation of the cache 5 and the backup unit 6a that backs up the operation of the operation monitoring unit 3. It is a magnetic disk device with a backup function (hereinafter referred to as HDD) to which a backup means 6b is added.

In FIG. 1, first, the data sent from the main body side (hereinafter referred to as a host device) is written in the cache 5 via the interface 2 controlled by the interface control unit 1. Then, the data written in the cache 5 is written in the magnetic disk medium 9 by the memory control unit 4 and the head / medium control unit 8 controlled by the CPU 7.

In the write cache operation, the time for writing data to the magnetic disk medium 9 is longer than the time for writing data to the cache 5. Further, since the host device recognizes that the data has been transferred when the data is written in the cache 5, the host device recognizes that the transfer is completed and turns off the power of the HDD.
The HDD may be in the middle of processing. Further, when the power of the HDD is turned off in the middle of the process, the data written up to that point and the remaining data in the cache 5 are erased. Therefore, in this embodiment,
Backup means 6a is added to the cache 5 so that data will not be erased even if the power of the HDD is turned off.

However, the power source of the HDD is turned off here.
When set to F, the processing data of the CPU 7 and the memory control unit 4 other than the cache 5 is erased, and the cache 5
Even the data management information such as how much data remains in the cache 5 and how much data is written in the cache 5 is erased. To solve this problem, the operation monitoring unit 3 that monitors the operation of the cache 5 is required.

The operation monitoring unit 3 monitors the data sent from the main body via the interface 2 and when it confirms that the data transfer from the main body to the cache 5 is completed, the last data is written in the cache 5. Holding address information. Further, the data written from the cache 5 to the magnetic disk medium 9 is constantly monitored. When the data is written on the magnetic disk medium 9, the data is read and the address information is held until the next data is written.

Since the cache 5 normally employs a FIFO (first in, first out) system, the data written first is sequentially output. Therefore, the data in the cache 5 can be managed by managing the address information of the first output data and the address information of the last data.

Therefore, if the data of the operation monitoring unit 3 is managed, even if the power is turned off, the writing is suspended based on the address information of the first and last data of the data in the cache 5. The rest of the data can be written from the location. Therefore, a backup means 6b is added to the operation monitoring unit 3 to hold the data of the operation monitoring unit 3.

These two backup means 6a, 6b
Is a backup power supply for holding the data in the operation monitoring unit 3 and the data in the cache 5, respectively, both of which are rechargeable batteries and a charging circuit for charging the batteries (both are shown in FIG. (Not shown).

Next, the processing inside the HDD when the power is turned off will be described.

FIG. 2 is a flow chart showing the flow of processing inside the HDD when the power is turned off. Referring to FIG.
First, the power of the HDD is turned on (step 21). Then, the CPU 7 is set (step 22). next,
The CPU 7 reads out the data of the operation monitoring unit 3 (step 23). Subsequently, the CPU 7 determines whether the address data exists in the cache 5 via the memory control unit 4 (step 24). If the cache 5 has no address data, the CPU 7
The start-up of D is started (step 27), and a series of processing is ended.

Further, in step 24, when address data exists in the cache 5, the CPU 7
The remaining data in the cache 5 is written to the magnetic disk medium 9 via the head / medium control unit 8 (step 2
5). When the writing of the data is completed (step 26), the CPU 7 starts the startup of the HDD (step 27), and the series of processes is completed.

[0018]

As described above, in the magnetic disk device with backup according to the present invention, the power of the device can be turned off even when the write cache is executed, that is, the power of the device can be turned off at any time, so that an unexpected power failure occurs. Also in the above, there is an effect that the data can be normally written in the magnetic disk device.

[Brief description of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a flowchart showing the flow of processing inside the HDD when the power is turned off.

[Explanation of symbols]

 1 interface control unit 2 interface 3 operation monitoring unit 4 memory control unit 5 cache 6a, 6b backup means 7 CPU 8 head / medium control unit 9 magnetic disk medium

Claims (1)

[Claims] 1. A magnetic disk device with a write cache, which monitors data sent from a higher-level device via an interface, and also addresses information of first output data and last data written in the cache. And an operation monitoring unit for monitoring data written in the magnetic disk medium from the cache, and information in the cache and information in the operation monitoring unit when the magnetic disk device is powered off. A magnetic disk device with a backup function, comprising: