Fujitsu MHW2060AC User Manual download pdf (Page 251)

6.3 Defect Processing

(3) Automatic alternating processing

This technology assigns a defective sector to a spare sector of a spare cylinder for

alternate assignment.

This device performs automatic alternating processing in the event of any of the

following errors.

• Automatic alternating processing is attempted for read error recovery by

reaching the specified retry cycle while a read error retry is in progress.

Before attempting automatic alternating processing, writing and reading of

already corrected data is repeated for the sector in which an error occurred. If

a read error does not occur during this reading operation, automatic

alternating processing is not performed.

• If error recovery is not successful even if a write fault error retry is executed,

automatic alternating processing is performed.

Figure 6.6 shows an example where automatic alternating processing is applied to

sector (physical) 5 with cylinder 0 and head 0.

Sector (physical)

Cylinder 0

Head 0

Defec-

tive

sector

(Not used)

Alternate cylinder 0

Head 0

This is assigned to an unassigned sector.

Already

assigned

779 780

Notes:

1. The alternate cylinder is assigned to an inner cylinder in each zone.

2. When an access request for sector 5 is issued, the sector assigned for

alternating processing of the alternate cylinder must be accessed instead of

physical sector 5.

If an access request for sectors after sector 5 is issued, seek is executed to

cylinder 0, head 0 in order to continue processing.

Figure 6.6 Automatic alternating processing

C141-E258 6-11

1 2 ... 246 247 248 249 250 251 252 253 254 255 256 ... 277 278

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Fujitsu MHW2060AC User Manual Page 251