Error detection/correction and fault detection/recovery – Pulse or data error handling – Memory testing
Reexamination Certificate
1998-07-24
2001-07-17
Tu, Christine T. (Department: 2133)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Memory testing
Reexamination Certificate
active
06263462
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a testing method and tester which are used for a hard disk drive (HDD) or the like, and particularly to a tester and a testing method in which a defective portion on a disk is detected in the manufacturing process of a magnetic disk drive, and a flagging is performed so that the particular portion is not used.
2. Description of Related Art
In the HDD used as the external storage device of an information processing unit, more miniaturization and reliability are required. Specifically, in the manufacturing process (test process) of a magnetic disk unit, there is a process for finding a defect such as a flaw occurring in a disk before the shipment, and performing a flagging so that the particular portion is not used. This process is called a Surface Analysis Test (SAT), which is a test for finding a defect on a disk and performing a flagging so that the particular portion cannot be used.
A flaw or the like having occurred in a disk is determined to be a defect when it cannot be read or written in an actual read/writing operation, and a flagging is performed so that the corresponding area is not used after shipped, thereby making the corresponding area invisible from the outside (unusable). Expecting the occurrence of defects in the disk, a predetermined amount of buffer is reserved, and the flagging is performed until the buffer is exhausted. The disk is determined to be a failure if the buffer is exhausted.
In the conventional SAT, the flagging is performed as follows.
In reading, if a read is performed and a plurality of errors occur in the same sector, that sector is flagged regardless of position in the sector. A read is performed, and, for instance, an error up to one per one megabyte is allowed.
In writing, if a write is performed and a plurality of errors occur in the same cylinder, that cylinder is flagged (or on a track basis) regardless of position in the cylinder. Generally, most of the write errors are caused by a servo trouble. Since the servo trouble causes errors in a plurality of portions rather than one portion, the use of the cylinder itself is inhibited.
In the SAT of the conventional disk drive, a sector is flagged if a plurality of errors occur in the same sector when a read is performed; and a cylinder is flagged if a plurality of errors occur in the same cylinder when a write is performed. Accordingly, sectors/cylinders which need not be flagged depending on the contents of the error are flagged and increase flagging results in the increase of disk failures, leading to reduction in the throughput.
It is the object of the present invention to provide a testing method and tester which can reliably flag errors which need to be flagged, and can largely decrease flags which are not necessary, thereby enabling disk failures to be reduced.
SUMMARY OF THE INVENTION
The tester of the present invention finds a defective portion in a disk, and performs a flagging so that the particular portion is not used. The tester comprises a detecting means for detecting the area where the defective portion has occurred, and a means for determining, based on the output of the detecting means, whether or not it is an error which randomly occurs. If it is an error which randomly occurred, the tester does not perform the flagging.
The tester of the present invention finds a defective portion in a disk, and performs a flagging so that the particular portion is not used. The tester comprises a detecting means for detecting the area where the defective portion has occurred, and a means for determining, based on the output of the detecting means, whether or not it is an error which occurs in a specific area with a predetermined frequency. If it is an error which occurs in a specific area with a predetermined frequency, the tester performs the flagging.
The tester of the present invention finds a defect in a disk, and performs a flagging so that the particular portion is not used. The tester comprises a detecting means for detecting the area where the defective portion has occurred, and a means for determining, based on the output of the detecting means, whether it is a repeatable error or a non-repeatable error, and performs the flagging if it is a repeatable error, and does not perform the flagging if it is a non-repeatable error.
The detecting means may detect the occurrence area within a sector in a read operation and the occurrence area within a cylinder in a writing operation. The determination means may judge based on the number of errors having occurred within a predetermined distance.
Further, the above tester may determine whether to perform or not to perform the flagging based on the number of errors having occurred. The above test may perform the flagging before products are shipped.
The testing method of the present invention performs a test for finding a defective portion having occurred in a disk, and performs a flagging so that the particular portion is not used. The testing method first detects the area where the defective portion has occurred, then determines, based on the detection result, whether or not it is a random error and does not perform the flagging if it is an error which randomly occurred.
The testing method of the present invention performs a test for finding a defective portion having occurred in a disk, and performs a flagging so that the particular portion is not used. The testing method first detects the area where the defective portion has occurred, then determines, based on the detection result, whether or not it is an error which occurs in a specific area with a predetermined frequency, and performs the flagging if it is an error which occurs in a specific area with a predetermined frequency.
The testing method of the present invention is a testing method for performing a test for finding a defective portion having occurred in a disk, and performing a flagging so that the particular portion is not used. The testing method first detects the area where the defective portion has occurred, then determines, based on the detection result, whether it is a repeatable error or a non-repeatable error, performs the flagging if it is a repeatable error, and does not perform the flagging if it is a non-repeatable error.
The above detection may be such that the occurrence area within a sector is detected in a read operation and the occurrence area within a cylinder is detected in a writing operation, and the above determination may be made based on the number of errors having occurred within a predetermined distance.
Other objects, features, and advantages of the present invention will be apparent from the accompanying drawings and from the detailed description below.
REFERENCES:
patent: 5798883 (1998-08-01), Kim
patent: 5943640 (1999-08-01), Macpherson
patent: 6005739 (1999-12-01), Yun
Hatano Akiro
Kagami Naoyuki
Matsubara Nobuya
International Business Machines - Corporation
Martin Robert B.
Tu Christine T.
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