Storage device with the ability to check for defects in same

Details Storage device with the ability to check for defects in same Storage device with the ability to check for defects in same

1997-04-07

2001-05-15

Young, W. R. (Department: 2651)

Dynamic magnetic information storage or retrieval

General processing of a digital signal

Data verification

C360S048000

Reexamination Certificate

active

06233108

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to a storage device equipped with a storage medium, a method of controlling the device, a storage system and a method of controlling the storage system.
In a magnetic storage device accommodating a storage medium such as a hard disk, it is usual for the storage medium to have defective storage areas that do not implement the storage function. To deal with a storage area having such a defect, substitution processing is executed. In substitution processing, a substitute storage area is prepared and is substituted for the defective storage area. In addition to substitution processing set when the product is shipped, substitution processing can be performed also with regard to defects that occur afresh during use of the device.
Substitution processing according to the prior art will be described with reference to FIG.
7
.
Shown in
FIG. 7
are a storage device
71
having ordinary storage areas
72
and substitute storage areas
73
set aside in order that substitution processing may be executed if some of the ordinary storage areas
72
develop defects. Shown at
74
is a substitute-area management area (referred to as a “defect list” or the like) for storing information indicating which areas have defects and which of the substitute storage areas
73
have been substituted for them.
Defective areas are of two types, namely a defective area
75
which existed from the outset at shipping of the storage device
71
from the factory, and a defective area
76
which developed subsequently during use of the device. When each of these areas is subjected to substitution processing, the defective area is replaced by a substitute storage area and information relating to the substitution is stored in the substitute-area management area
74
.
By way of example, Japanese Patent Application Laid-Open (Kokai) No. 4-266117 describes a storage device in which the storage areas of the storage device are monitored to determine, at reading or writing of data, the number of reading/writing retries and occurrence of errors per each storage area. By recording the number of read/write retries associated with each storage area of the storage device, storage areas deemed to be likely to fail or storage areas in which defects have occurred during use can be replaced by substitute storage areas automatically.
However, with the conventional storage device of this kind, substitution processing for dealing with defects that have occurred anew during use of the device is executed in response to an instruction from the user.
Further, as described in Japanese Patent Application Laid-Open No. 4-266117, the detection and prediction of the occurrence of defects is limited to storage areas actually accessed. More specifically, the detection and prediction of defects in storage areas is not carried out with regard to storage areas currently vacant and unused but to which data are likely to be written in the future or with regard to storage areas in which data exist but which will not be read or written for an extended period of time.
Another problem is that satisfactory detection and prediction of the occurrence of defects cannot be carried out because such detection and prediction is performed only when a read instruction or write instruction is implemented as an actual accessing operation.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a storage device, a method of controlling the same and a storage system in which the detection and prediction of the occurrence of defects in all storage areas of the storage device can be performed accurately and automatically, and in which a storage area that has become defective can be replaced by another storage area automatically.
A further object of the present invention is to provide a storage device, a method of controlling the same and a storage system in which accessing as by an ordinary read instruction or write instruction can be executed while detection and prediction of the occurrence of defects in storage areas is carried out.
According to the present invention, the foregoing objects are attained by providing a storage device equipped with a storage medium, comprising checking means for checking for defects in storage areas by performing reading and writing of data over all storages areas constituting the storage medium, accumulating means which, when an error that has occurred by checking performed by the checking means is an error for which retry is possible, is for accumulating the number of times this has occurred, and detecting means for detecting fault locations in the storage areas based upon the type of error that has occurred by checking performed by the checking means or the number of occurrences accumulated by the accumulating means.
In a preferred embodiment, the device further comprises substitution means for substituting another storage area for a storage area having a defect detected by the detecting means. Providing the substitution means makes it unnecessary for the substitution to be performed by the user.
In a preferred embodiment, the detecting means detects a storage area under examination as being a defective location if the number of occurrences accumulated by the accumulating means exceeds a predetermined number or if the error that has occurred by checking performed by the checking means is an error for which retry is impossible.
In a preferred embodiment, the storage device has a control instruction for checking for defects in storage areas by performing control in such a manner that instructions from elsewhere are not accepted during execution of checking by the checking means, wherein the checking means checks for defects in the storage areas using this control instruction. By employing this control instruction, storage areas other than storage areas being checked are capable of accepting instructions from elsewhere.
In a preferred embodiment, the storage device further comprises holding means for holding data read out by the checking means, wherein the checking means checks for defects of the storage areas by re-reading data out of a storage area after it has been checked by the checking means and comparing the read data and the data held by the holding means. Adopting this arrangement makes it possible to improve the accuracy of the check performed by the checking means.
In a preferred embodiment, the check performed by the checking means is executed at predetermined times.
According to the present invention, the foregoing objects are attained by providing a storage system equipped with a plurality of storage devices, comprising checking means for checking for defects in storage areas by performing reading and writing of data over all storages areas constituting a storage medium provided in each storage device of the plurality thereof, accumulating means which, when an error that has occurred by checking performed by the checking means is an error for which retry is possible, is for accumulating the number of times this has occurred, detecting means for detecting fault locations in the storage areas based upon the type of error that has occurred by checking performed by the checking means or the number of occurrences accumulated by the accumulating means, monitoring means for monitoring status of detection of each storage device of the plurality thereof by the detecting means, and substitution means for substituting one storage device for another in dependence upon status of detection monitored by the monitoring means.
According to the present invention, the foregoing objects are attained by providing a method of controlling a storage device equipped with a storage medium, comprising a checking step of checking for defects in storage areas by performing reading and writing of data over all storages areas constituting the storage medium, an accumulating step which, when an error that has occurred by checking performed at the checking step is an error for which retry is possible, is a step of accumulating the number of times this has occurred, and a

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