JPS62248171A - Errored track substituting method for magnetic disk - Google Patents

Abstract

PURPOSE:To speed up the information processing by storing errored track substitution information and track state information to decrease the times of accessing a magnetic disk even in case there is an errored track. CONSTITUTION:In the magnetic disk 10, in addition to normal tracks for data, a substitution area and an index area are provided, and an errored track substitution information table 13 to show the correspondence relation between the errored track 11 and a substitution track 12 is provided. In a memory 4 incorporated in an information processor, a table 41 whose content is the same as that of the table 13 and a track state information table 42 are stored. Following the starting of a magnetic disk device, the table 13 is transferred to the memory 4, and the states of all the tracks are stored in the table 42. When an errored track is accessed, a substitution track is selected by one accessing through the tables 41 and 42.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for replacing error tracks on a magnetic disk.

[Conventional technology]

Magnetic disks are widely used primarily as external storage devices for information processing devices.

A magnetic head is used to read or write data to a magnetic disk.

A magnetic head accesses a designated track on a magnetic disk in accordance with an input/output command to read or write data.

However, among the many tracks of such a magnetic disk, some may be damaged for some reason, causing input/output problems.

Conventionally, therefore, a method has been adopted in which the track in which the input/output failure occurs is treated as an error track, and a substitute track prepared separately and preliminarily on the magnetic disk is used as a substitute for the track.

In this method, in addition to an index area for storing data such as an index and a data area for storing regular data, a preliminary alternative area is provided on the magnetic disk. This alternative area is made up of a predetermined number of alternative tracks.

When executing a data input/output command to the magnetic disk, the tracks of the data area are usually accessed first. Here, when an input/output command for an error track is executed, at that stage, for example, an I-O error occurs, and the track is recognized as an error track.

On the other hand, the index area stores an error track replacement information table that displays the correspondence between error tracks in the data area and their replacement tracks. If the track on which the input/output command was executed is recognized as an error track, this error track alternative information table is referenced and
A track address of a given alternate track of the alternate area is obtained.

In this way, the track address of this alternative track is accessed, the input/output command is executed again, and data reading or writing is completed.

[Problem that the invention seeks to solve]

However, in such a conventional method for replacing an error track of a magnetic disk, it is recognized at step S2 that the track is an error track only after an input/output command is executed for the error track.

Therefore, when executing an input/output command, three accesses may be required: access to the error track, access to refer to the error track alternative information table, and access to the alternative track. The problem was that the number of inputs and outputs was large (as a result, the temporal performance of disk access was poor).

The present invention has been made in view of the above points, and it is an object of the present invention to provide a method for replacing error tracks on a magnetic disk, which reduces the number of times the magnetic disk is accessed and speeds up the processing. be.

[Means for solving problems]

The error track replacement method for a magnetic disk according to the present invention includes an error track replacement information table that displays the correspondence between error tracks existing on the magnetic disk and their replacement tracks after the magnetic disk device is started, and all of the above-mentioned magnetic disks. Create a track status information table in memory that displays the status of the track in the track status information table, and if an error track is displayed in the track status information table, refer to the error track alternative information table and select an alternative track. It is characterized by executing input/output.

[Effect]

In this way, a track status information table that displays the status of all tracks on the magnetic disk is created on the memory, and by referring to this table, it can be immediately determined whether or not the track to be accessed is an error track.

If this is an error track, an alternative track is checked by referring to the error track alternative information table similarly created on the memory.

By accessing alternative tracks on the magnetic disk in this way, the number of accesses to the magnetic disk is reduced, and data can be written or read at high speed.

〔Example〕

The figure is a block diagram of an information processing apparatus suitable for implementing the method for replacing error tracks on a magnetic disk according to the present invention.

This device includes a magnetic disk 10, an input/output control mechanism 1 for controlling data input/output to the magnetic disk, an error track alternative processing mechanism 2, an error track information creation mechanism 3, and a memory 4.

The input/output control mechanism 1, the error track alternative processing mechanism 2, and the error track information creation mechanism 3 are composed of a microprocessor, an execution memory, and the like.

In addition to regular tracks for writing data, the magnetic disk 10 is provided with an alternative area for alternative tracks and an index area. In the figure, error tracks 11 where a failure has occurred are indicated as T100, T150, and T300.
The alternative tracks 12 are indicated as 31-Sn. Also, in the index area of this magnetic disk 10, there is an error track 11.
An error track replacement information table 13 is provided that shows the correspondence between the track and the replacement track 12.

On the other hand, the memory 4 is a high-speed memory made of a semiconductor element or the like incorporated in the information processing device, and a part of the memory 4 includes an error track replacement information table 1 stored in the magnetic disk 10.
An area is reserved for storing a table 41 with the same contents as 3 and a track status information table 42.

This track status information table 42 is based on the magnetic disk 1
This is a table that displays the status of all 0 tracks, and is composed of a data group containing, for example, 1" for error tracks and 0 for other tracks.

Using such an apparatus, the method of the present invention is carried out as follows.

First, when the magnetic disk device 10 is started, the error track information creation mechanism 3 reads the error track replacement information table 13 stored in the magnetic disk 10 and transcribes it as is into a predetermined area of the memory 4.

Before and after this operation, the error track information creation mechanism 3 examines all the tracks on the magnetic disk 10, knows the track addresses of the error tracks T100, T150, and T300 among them, and writes the track status information table 42.
Create. And this track status information table 42
is stored in a predetermined area of the memory 4.

In this embodiment, the error track T100 is the substitute track S1, the error track T150 is the substitute track S2, and the error track T300 is the substitute track S3.
has been replaced by

Therefore, the track status information table 42 shows error track T100 among all the tracks. Only the data corresponding to T150 and T300 will be set to "1", and the others will be set to O". Note that n alternative tracks are prepared for this magnetic disk 10, and up to n pieces of error can be detected. The presence of trucks is allowed.

Here, when the input/output control mechanism 1 issues a data input/output request, the processing is passed to the error track alternative processing mechanism 2.

The error track replacement processing mechanism 2 first uses the track status information table 42 in the memory 4 to check whether the track address to be accessed included in the input/output command is for accessing an error track.

If this is not an error track, the magnetic disk is immediately accessed using that track address. In this way, input/output commands to that track are executed.

On the other hand, if this track address is for accessing the error track T100, for example, the error track replacement information table 41 in the memory 4 is referred to. As a result, the magnetic disk 10 is accessed using the track address of the alternative track S1. In this way, input/output commands to that track are executed.

As described above, alternative processing such as referencing the error track alternative information table is performed using high-speed memory, and even if the track address for which the input/output request was made is for a normal track, it may be for an error track. However, disk access is completed only once.

[Modified example]

The method for replacing error tracks on a magnetic disk according to the present invention is not limited to the above embodiments.

The formats of the error track replacement information table and the track status information table may be in various other formats. Further, the error track alternative processing mechanism, the error track information creation mechanism, etc. are not necessarily separate mechanisms, but may be integrated.

〔Effect of the invention〕

According to the method for replacing error tracks on a magnetic disk of the present invention as described above, it becomes possible to reduce the number of disk accesses to a magnetic disk on which an error track exists and to access the disk at high speed.

[Brief explanation of drawings]

The figure is a block diagram of an information processing apparatus suitable for implementing the method for replacing error tracks on a magnetic disk according to the present invention. 1... Input/output control mechanism, 2... Error track alternative processing mechanism, 3...
... Error track information creation mechanism, 4 ... Memory, 10 ... Magnetic disk, 11 ... Error track, 12 ... Alternative track, 13. 41...Error track alternative information table, 42...Track status information table. Applicant: NEC Corporation Representative

Claims (1)

[Claims] An error track alternative information table that displays the correspondence between error tracks existing on the magnetic disk and their alternative tracks after the magnetic disk device is started; and a track status information table that displays the status of all tracks on the magnetic disk. and when an error track is displayed in the track status information table, refer to the error track alternative information table,
A method for replacing an error track of a magnetic disk, characterized by performing input/output on a replacement track.