JP2001060370A - Service life judging system for magnetic disk device - Google Patents

Service life judging system for magnetic disk device

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Publication number
JP2001060370A
JP2001060370A JP11237135A JP23713599A JP2001060370A JP 2001060370 A JP2001060370 A JP 2001060370A JP 11237135 A JP11237135 A JP 11237135A JP 23713599 A JP23713599 A JP 23713599A JP 2001060370 A JP2001060370 A JP 2001060370A
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Japan
Prior art keywords
magnetic disk
ecc error
step
life
number
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP11237135A
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Japanese (ja)
Other versions
JP3486863B2 (en
Inventor
Masayoshi Ueno
Hiroyuki Yajima
政義 上野
博之 矢島
Original Assignee
Nec Corp
日本電気株式会社
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Publication date
Application filed by Nec Corp, 日本電気株式会社 filed Critical Nec Corp
Priority to JP23713599A priority Critical patent/JP3486863B2/en
Publication of JP2001060370A publication Critical patent/JP2001060370A/en
Application granted granted Critical
Publication of JP3486863B2 publication Critical patent/JP3486863B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Abstract

(57) [Summary] To determine the life of a magnetic disk device, for example, a video magnetic disk device. SOLUTION: When an ECC error occurs at the time of data reading, an ECC error 16 on continuous sectors on the same track, and an ECC error 1 across tracks in the same zone.
7 and an ECC error 18 across zones is determined, and the life of the magnetic disk device is determined based on the physical continuity of the ECC error.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive, and more particularly, to a video magnetic disk drive having a function of notifying a replacement time when a service life is reached.

[0002]

2. Description of the Related Art Conventionally, as this type of magnetic disk device, for example, a device described in Japanese Patent Application Laid-Open No. 6-295519 is known. The number of times is monitored, and when one of them exceeds a preset reference value, it is determined that the magnetic disk device needs to be replaced, that is, the life has expired.

[0003]

By the way, there are individual differences in the magnetic disk devices, and even if they are operated under the same condition, they cannot be said to have the same life.
Therefore, as described above, it is difficult to accurately predict the life of each magnetic disk device from the total energization time of the spindle motor and the cumulative number of contact start / stop times.

Further, in the conventional magnetic disk drive, when one of the total energizing time of the spindle motor and the total number of contact start / stop times exceeds a preset reference value, it is determined that the magnetic disk drive has reached the end of its life. Although it is determined, such a method cannot cope with a case where the life has expired earlier than expected. That is, when the life of the magnetic disk device is unexpectedly short, there is a problem that it is not possible to correctly determine when to replace the magnetic disk device.

An object of the present invention is to provide a magnetic disk drive capable of accurately determining the life.

[0006]

According to the present invention, a first step of obtaining ECC error information at the time of reading data, which is used in determining the life of a magnetic disk drive, and based on the ECC error information, An unrecoverable ECC error is the first number of sectors (u) predetermined on the same track
A second step of determining whether the magnetic disk device has reached the end of its life if the unrecoverable ECC error continuously exists on the same track for the first number of sectors (u) or more. And a third step of determining the life of the magnetic disk device.

Further, according to the present invention, it is used for determining the life of the magnetic disk device,
A first step of obtaining CC error information; and a second step in which an unrecoverable ECC error or a recoverable ECC error is determined on the same track based on the ECC error information.
A second step of determining whether or not there is a continuous number of sectors (w) or more, and wherein the unrecoverable ECC error or the recoverable ECC error is the same as the second sector number (w) on the same track. And a third step of determining that the magnetic disk device has reached the end of its life if the magnetic disk device exists continuously as described above.

Further, according to the present invention, a first step for obtaining the ECC error information at the time of reading data, which is used for determining the life of the magnetic disk device, and an unrecoverable ECC error based on the ECC error information A second step of determining whether or not an error exists on the same track by a predetermined first sector number (u) or more; and the irrecoverable ECC error is on the same track by the first sector number (u). (U) Unrecoverable or unrecoverable ECC errors or recoverable ECC errors continue on the same track for a second sector number (w) greater than the first sector number (u). A third step of determining whether or not the ECC error is present, and the unrecoverable ECC error or the recoverable ECC error is continuously on the same track for the second sector number (w) or more. Life determination method of the to standing magnetic disk apparatus a magnetic disk apparatus characterized by a fourth step of determining that the life can be obtained.

In addition, according to the present invention, the first step is used to determine the life of the magnetic disk device and obtains ECC error information when reading data. A second step of determining whether or not an ECC error is continuously present in the same sector position on the magnetic disk for a predetermined first number of tracks (v) or more; A third step of determining that the magnetic disk device has reached the end of its life if the same number of tracks continuously exist at the same sector position on the disk as the first number of tracks (v) or more. A life determination method is obtained.

According to the present invention, there is provided a first step for obtaining the ECC error information at the time of reading data, which is used in determining the life of the magnetic disk drive, and an unrecoverable ECC error based on the ECC error information. A second step of determining whether or not an error or a recoverable ECC error is present at the same sector position on the magnetic disk by a predetermined second number of tracks (x) or more;
A third step of determining that the magnetic disk device has reached the end of its life if a CC error or the recoverable ECC error exists at the same sector position on the magnetic disk or more than the second number of tracks (x). And a life discrimination method for the magnetic disk device characterized by the following.

According to the present invention, the first step of obtaining the ECC error information at the time of reading data, which is used in determining the life of the magnetic disk drive, and the step of detecting an unrecoverable ECC error based on the ECC error information is performed. A second step of determining whether or not the same sector position on the magnetic disk is continuously present for a predetermined first number of tracks (v) or more, and when the unrecoverable ECC error is detected on the magnetic disk. Unless the first track number (v) is present continuously at the same sector position, an unrecoverable ECC error or a recoverable ECC error occurs at the same sector position on the magnetic disk. A third step of determining whether or not there is a second track number (x) greater than or equal to), and the unrecoverable ECC error or the recoverable ECC error. A fourth step of determining that the life of the magnetic disk device is reached when the number of tracks is equal to or more than the second number of tracks (x) at the same sector position on the magnetic disk. A scheme is obtained.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

Referring to FIG. 1, a magnetic disk drive for video shown in FIG. 1 includes a preamplifier (PreAmp) 1, a disk enclosure (DE) 2, a data read / write channel processing unit (RW-Channel) 3, a spindle motor / voice coil motor. Driver (SPM / VCM D
river) 4, an interface unit (I
/ F) 5, Magnetic disk drive controller (HDC)
6, an MPU 7, a life information transmission unit 8, and a RAM 9.

In the example shown, the read data signal read from the DE 2 is amplified by the preamplifier 1 and then digitally encoded by the data read / write channel processing unit 3.
Then, the digitally encoded signal is sent to the HDC 6 as read data.

In the HDC 6, the ECC in the read data
(Error Correction Code) is compared with the data to check for a data error.
When a bit error is detected as a result of the check, the HDC 6 attempts to repair the data using the ECC.

On the other hand, when an ECC error is detected in the read data, the position of the sector on the disk and the ECC
(Error information) indicating whether or not data restoration by the MPU 7 has been successful is temporarily recorded in the RAM 9 by the MPU 7.
Then, using the error information, the life of the magnetic disk device is determined as described later.

By the way, in the magnetic disk apparatus for video, it is necessary to process a large amount of data in a short time at the time of reproducing the video image. Therefore, even if a read data error occurs during the reproduction, the retry is not performed and the next sector is read. Data read may be performed. In such a case, as the magnetic disk device is used, an area that cannot be partially read occurs due to an adhering substance or a scratch on the disk surface, and if a data error occurs in the sector being read, the video quality during reproduction is reduced. Will be greatly affected.

In general, the head of a magnetic disk drive moves in a direction perpendicular to the rotation of the disk.
When the head contacts the disk surface, linear scratches are likely to occur. For this reason, when the read data error sector physically occurs continuously on a part of the disk in an arbitrary head of the video magnetic disk device, the error range is analyzed, and when the error sector continuity is high. Assuming that the disk surface has a fatal flaw, a notification is given that the magnetic disk device has reached the end of its life as described later.

In FIG. 3, continuous sectors on the same track indicated by reference numeral 16 in FIG. 3, continuous sectors on adjacent tracks in the same zone indicated by reference numeral 17 in FIG. 3 of consecutive sectors between tracks across the zone indicated by number 18
There are street patterns.

Here, in consideration of each of these patterns,
The following four criteria are used to determine whether the drive has reached the end of its life.

(1) When an unrecoverable ECC error is present continuously for u sectors or more on the same track, it is determined that the drive has expired.

(2) When an unrecoverable ECC error is continuously present in the same sector position on the disk for v tracks or more, it is determined that the drive has expired.

(3) If an unrecoverable ECC error or a recoverable ECC error is present continuously for w sectors or more on the same track, it is determined that the drive has expired.

(4) If an unrecoverable ECC error or a recoverable ECC error exists continuously in the same sector position on the disk for x tracks or more, it is determined that the drive has reached the end of its life.

The values of u, v, w, and x are set in accordance with the reliability required for the drive and the quality of the video reproduced video. In general, the above-described determination reference values are set so that w> u and x> v.

By using the above criterion, it is possible to detect a bad sector that is continuous over a wide area, such as a scratch caused by contact between the disk and the head. For example, if the determination reference value v in the above (2) is set to 4, as shown in FIG.
In all of 11, 12, and 13, when an unrecoverable ECC error occurs at the time of reading, it can be determined that the magnetic disk device has reached the end of its drive life.

Next, a method for confirming the continuity on the disk of a sector where a data error has occurred will be described.

FIG. 5 shows an example of an error sector that crosses tracks in the same zone. In the track 28 immediately before the sector where the data error has occurred, the serial number of the ECC error sector counted from the index header (INDEX) 20 is m, and relative position information for comparing the continuity of the ECC error sector on the disk. As
ECC error sector 23 during the last track 28 the head position of the sector to indicate what number of sectors counted from index header 20 and A m, a trailing position and A m +1. The serial number of the ECC error sector in the currently read track 29 is set to n, and as the relative position information for comparing the continuity of the ECC error sector on the disk, the currently generated ECC error sector 2 is used.
7 is the current track 29 counted from the index header 20
In order to indicate the order of the sector, the start position of the sector is B n , and the tail position is B n +1. Further, let k be the maximum value of the number of data sectors per track in all tracks on the disk.

Referring to FIG. 7, when the reading of the disk is started, the variables are initialized in the reading (step 101). That is, the MPU 7 is in the RAM 9
Area provided above (here referred to as counter) C
1 to C k , D 1 to D k , E 1 to E k , F 1 to F k , S,
And T are reset. Then, as described with reference to FIG. 1, the reading of the sector data is performed (step 102). The HDC 6 determines whether or not the read track has changed (step 103).
It is determined whether a C error has occurred (step 10).
6).

If it is determined in step 103 that the read track has changed, the MPU 7
, And T, the value of the counter E (suffix omitted) is assigned to the counter C (suffix omitted), and the value of the counter F (suffix omitted) is assigned to the counter D (suffix omitted) (step 10).
4). Then, counters E (suffix omitted) and F
Substitute zero for (suffix omitted). Thereafter, step 106 is performed.

In step 106, if no ECC error has occurred, the process returns to step 102. On the other hand, E
When a CC error occurs, if Bn = Bn-1 + 1, it is assumed that the ECC errors are continuous on the same track. Then, the HDC 6 determines whether error correction can be performed by the ECC (Step 107).
If the error can be corrected, the process proceeds to FIG.

If the error cannot be corrected, the MPU 7 determines whether there is an uncorrectable or correctable ECC error in the sector immediately before the same track (step 10).
8). If there is such an ECC error, if the ECC error cannot be restored, the counter S indicating the number of consecutive unrecoverable ECC error sectors in the current track and the unrecoverable or recoverable EC in the current track.
One is added to each of the counters T indicating the number of consecutive C error sectors (step 109). On the other hand, in step 108, if there is no uncorrectable or correctable ECC error in the sector immediately before the same track, the counters S and T are incremented by one.
Is substituted (step 110).

Next, the MPU 7 first sets the counter S to S
It is determined whether or not ≧ u (step 111). If S ≧ u, the life information transmitting unit 8 is operated,
The life is notified to the outside (step 113). On the other hand, if S <u, the MPU 7 sets the counter T to T ≧ w
Is determined (step 112). And
If T ≧ w, step 113 is executed. On the other hand, T
If <w, go to FIG.

Referring to FIG. 8, step 11 shown in FIG.
In T2, if T <w, the MPU 7 determines that uncorrectable or correctable E
It is determined whether there is a CC error (step 11)
4). If there is such an ECC error, the counter C m
Substituting the value obtained by adding 1 to the value in the counter E n and F n. On the other hand, if there is such an ECC error, assigns 1 to a counter E n and F n. And MPU7,
Counter E n is then determined whether the E n ≧ v (step 117), if it is E n ≧ v, by operating the life information transfer unit 8, performs lifetime notification to the outside (step 1
19). On the other hand, if it is E n <v, MPU 7, the counter F n determines whether or not F n ≧ x (Step 1
18). Then, if F n ≧ x, step 119 is executed. On the other hand, if Fn <x, the process proceeds to FIG.
That is, the process returns to step 102.

Referring to FIG. 9, step 10 shown in FIG.
7, if the data can be corrected by the ECC, an uncorrectable or correctable EC
It is determined whether there is a C error (step 120).
If there is such an ECC error, 1 is added to the counter T (step 121). On the other hand, if there is no such ECC error, 1 is substituted for the counter T (step 1).
22).

Thereafter, the MPU 7 determines that the counter T is T ≧ w.
(Step 123), and if T <w, it is determined whether there is an uncorrectable or correctable ECC error in an adjacent sector of the immediately preceding track (step 124). When there is such an ECC error, it substitutes the value obtained by adding 1 to the value of the counter D m in the counter F n (step 125). On the other hand, if there is such an ECC error, it assigns 1 to a counter F n (step 126).

[0037] After that, MPU7, the counter F n is F n
It is determined whether or not ≧ x (step 127), and Fn
If ≧ x, the life information transmitting unit 8 is operated to notify the life to the outside (step 128). On the other hand, Fn
If <x, the process proceeds to FIG. That is, step 10
Return to 2. If T ≧ w in step 123, the MPU 7 executes step 128.

As is clear from the above description, in the first example of the present invention, when an ECC error occurs during data reading, if Bn = Bn-1 + 1 , the ECC error is on the same track. And the following processing is performed.

(1) When the generated ECC error is incapable of data recovery, a counter S indicating the number of consecutive unrecoverable ECC errors in the current track and an unrecoverable or recoverable ECC error in the current track. One is added to each of the counters T indicating the number of consecutive sectors.

(2) When the data of the generated ECC error can be recovered, 1 is added to the counter T.

Then, the counter S ≧ u or the counter T
When ≧ w, the magnetic disk device determines that the life has expired, and notifies the outside by the life information transmitting unit.

On the other hand, unless an ECC error occurs during data reading and Bn = Bn-1 + 1, first of the ECC error occurrence location data in the previous track, the data of the sector continuous across the tracks is read. The condition, ((B n <A
Only data that satisfies m + 1) and ( Bn + 1> Am )) is extracted (see FIG. 4).

The ECC error sector on the immediately preceding track is an unrecoverable EC that continues across the tracks.
A counter indicating the total number of C error sectors is represented by a counter C m and an unrecoverable or recoverable E which is continuous across tracks.
A counter indicating the total number of CC error sectors is defined as a counter Dm . Further, for the ECC error sector on the track that is currently being read, the unrecoverable E that continues across the tracks is unrecoverable.
Counter E n the counter indicating the CC error total number of sectors,
Counter irreparable or counter indicating the ECC error sector total possible repairs continuously across the track F n
If the currently read track is in the same zone as the immediately preceding track and A m = B n , then (1) When an unrecoverable ECC error occurs, the counter C m is incremented by one. counter E n and counter F n
Substitute for

[0044] (2) when the recoverable ECC error occurs, substituting one plus the counter D m in the counter F n.

Then, the counter E n ≧ v or the counter F
When n ≧ x, the magnetic disk device determines that the life has expired, and notifies the outside by the life information transmitting unit.

Next, a second example of the present invention will be described.

In this example, as indicated by reference numeral 18 in FIG.
This is a determination method when an ECC error sector is continuous over a plurality of zones.

Referring to FIG. 6 and FIGS. 7 to 9,
When an ECC error occurs during data reading, first, among the ECC error occurrence location data in the previous track, the condition of the sector that continues over the tracks, that is, ((B n <A
Only data that satisfies m + 1) and ( Bn + 1> Am )) is extracted (see FIG. 4).

Then, the ECC error section extends across zones.
Are adjacent to each other, that is, ((((Am
Bn) And (Am≤Bn+1)) or ((Am+ 1 ≧
Bn) And (Am+ 1 ≦ Bn+1)) or ((Am
Bn) And (Am+ 1 ≧ B n+1)))
(1) When an unrecoverable ECC error occurs,
TA Cm1 is added to the counter EnAnd counter F
n(Step 115 in FIG. 8).

[0050] (2) When a recoverable ECC error occurs, substituting one plus the counter D m in the counter F n (step 125 in FIG. 9).

Then, the counter E n ≧ v (step 117 in FIG. 8) or the counter F n ≧ x (step 1 in FIG. 8)
18, when it is determined in step 127 in FIG. 9 that the magnetic disk device has reached the end of its life, a notification is sent to the outside by the life information transmitting device (step 11 in FIG. 8).
9, step 128 in FIG. 9).

Next, a third example of the present invention will be described.

In the first example, the sector position on the disk and its physical continuity are determined based on the number of the sector counted from the index header. In the third example, the sector position on the disk is determined. Using the corner position from the index header, the continuity of the error sector across the tracks is determined.

In FIG. 10, the index header 20
H-th sector 205 counting along track from 7
In, when an ECC error occurs, when the number of data sectors per track zone the sector 205 exists and k z, sector 205 start angular position 208 (h
-1) / k z , and the angular position 209 of the tail of the sector is determined by h / k z .

The continuity of the sector is determined in the same manner as in the first example by comparing the thus obtained corner positions of the head and tail of the sector with the respective corner positions of the sector of the immediately preceding track. To determine the life.

[0056]

As described above, according to the present invention, the life of the magnetic disk device is determined from the actual occurrence status of the ECC error, so that the life of the magnetic disk device can be accurately known. There is an effect that the reliability of the magnetic disk device can be improved.

Further, according to the present invention, the actual ECC error is monitored in real time when reading the disk, so that even if the life of the magnetic disk device is much shorter than usual, the life can be detected reliably. effective.

Further, according to the present invention, the continuous error on the same track and the error across the tracks are separately monitored. Therefore, the life criterion is adjusted according to the difference in the use environment and the characteristics of each device. There is an effect that can be.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a magnetic disk drive according to the present invention.

FIG. 2 is a diagram showing an example of a scratch across a plurality of tracks on a disk.

FIG. 3 is a diagram showing an example of occurrence of an ECC error on a disk.

FIG. 4 is a diagram showing an example in which sectors on adjacent tracks are continuous.

FIG. 5 is a diagram showing an example of an error sector that crosses tracks in the same zone.

FIG. 6 is a diagram illustrating an example of an error sector of a track that crosses zones.

FIG. 7 is a flowchart illustrating an example of a life determination method according to the present invention.

FIG. 8 is a flowchart illustrating an example of a life determination method according to the present invention.

FIG. 9 is a flowchart illustrating an example of a life determination method according to the present invention.

FIG. 10 is a diagram illustrating a method of comparing sector positions on a disk.

[Explanation of symbols]

1 Preamplifier (PreAmp) 2 Disk enclosure (DE) 3 Read / write channel control unit (RW-Channel)
1) 4 spindle motor / voice coil motor driver (SPM / VCM Driver) 5 external interface (I / F) 6 magnetic disk device controller (HDC) 7 MPU 8 life information transmission unit 9 RAM

Continued on the front page (51) Int.Cl. 7 Identification symbol FI Theme coat II (reference) G11B 19/02 501 G11B 19/02 501J

Claims (6)

    [Claims]
  1. A first step of obtaining ECC error information at the time of data reading, which is used when determining the life of the magnetic disk device, and an unrecoverable ECC error based on the ECC error information is recorded on the same track. A second step of determining whether or not there is a predetermined first number of sectors (u) or more, and wherein the unrecoverable ECC error is continuous on the same track for the first number of sectors (u) or more. And a third step of determining that the magnetic disk drive has reached the end of its life if present.
  2. 2. A first step of obtaining ECC error information at the time of data reading, which is used when determining the life of a magnetic disk device, and an unrecoverable ECC error or a recoverable ECC based on the ECC error information. A second step of determining whether or not errors are continuously present on the same track for a predetermined second number of sectors (w) or more;
    The unrecoverable ECC error or the recoverable ECC
    A third step of determining that the magnetic disk device has reached the end of its life if an error is continuously present on the same track for the second number of sectors (w) or more. method.
  3. 3. A first step of obtaining ECC error information at the time of data reading, which is used when determining the life of a magnetic disk device, and an unrecoverable ECC error based on the ECC error information is recorded on the same track. A second step of determining whether or not there is a predetermined first number of sectors (u) or more, and wherein the unrecoverable ECC error is continuous on the same track for the first number of sectors (u) or more. ECC error that cannot be repaired if it does not exist or ECC that can be repaired
    A third step of determining whether or not an error is continuously present on the same track for a second sector number (w) greater than the first sector number (u); and
    When the CC error or the recoverable ECC error continuously exists on the same track for the second sector number (w) or more, the magnetic disk device is determined to have reached the end of its life.
    And a step of determining the life of the magnetic disk drive.
  4. 4. A first step of obtaining ECC error information at the time of reading data, which is used when determining the life of a magnetic disk device, and detecting an unrecoverable ECC error on the magnetic disk based on the ECC error information. A second step of judging whether or not the same sector position continuously exists for a predetermined first number of tracks (v) or more, and the case where the irrecoverable ECC error is in the same sector position on the magnetic disk If the magnetic disk device is determined to have reached the end of its service life if the number of tracks continuously exceeds the first number of tracks (v), the third determination is made.
    And a step of determining the life of the magnetic disk drive.
  5. 5. A first step of obtaining ECC error information at the time of data reading, which is used when determining the life of a magnetic disk device, and an unrecoverable ECC error or a recoverable ECC based on the ECC error information. A second step of determining whether or not an error exists in the same sector position on the magnetic disk by a predetermined second number of tracks (x) or more; and the unrecoverable ECC error or the recoverable ECC. A third step of determining that the magnetic disk device has reached the end of its life if an error exists at the same sector position on the magnetic disk as the second track number (x) or more. Life determination method.
  6. 6. A first step for obtaining the ECC error information at the time of data reading, which is used in determining the life of the magnetic disk device, and detecting an unrecoverable ECC error on the magnetic disk based on the ECC error information. A second step of judging whether or not the same sector position continuously exists for a predetermined first number of tracks (v) or more, and the case where the irrecoverable ECC error is in the same sector position on the magnetic disk Unless the first track number (v) is present continuously, an unrecoverable ECC error or a recoverable ECC error is greater than the first track number (v) at the same sector position on the magnetic disk. Second track number (x)
    A third step of judging whether or not there is the above, and determining that the unrecoverable ECC error or the recoverable ECC error exists in the same sector position on the magnetic disk by the second track number (x) or more. A fourth step of determining that the magnetic disk device has reached the end of its life.
JP23713599A 1999-08-24 1999-08-24 Life determination method for magnetic disk drive Expired - Fee Related JP3486863B2 (en)

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Application Number Priority Date Filing Date Title
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Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP23713599A JP3486863B2 (en) 1999-08-24 1999-08-24 Life determination method for magnetic disk drive

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SG102715A1 (en) * 2002-06-28 2004-03-26 Toshiba Kk Method and apparatus for event management in a disk drive

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SG102715A1 (en) * 2002-06-28 2004-03-26 Toshiba Kk Method and apparatus for event management in a disk drive
US6950255B2 (en) 2002-06-28 2005-09-27 Kabushiki Kaisha Toshiba Method and apparatus for event management in a disk drive

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Publication number Publication date
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