1 spare area, 2 alternating defective sectors – FUJITSU MPB3052AT User Manual
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6.4.1
Spare area
Following two types of spare area are provided for every physical head.
1) Spare cylinder for sector slip:
used for alternating defective sectors at formatting in shipment (11 cylinders/head)
2) Spare cylinder for alternative assignment:
used for alternative assignment by automatic alternative assignment. (4 cylinders/head)
6.4.2
Alternating defective sectors
The two alternating methods described below are available:
(1)
Sector slip processing
A defective sector is not used and is skipped and a logical sector address is assigned to the
subsequent normal sector (physically adjacent sector to the defective sector).
When defective sector is present, the sector slip processing is performed in the formatting.
Figure 6.7 shows an example where (physical) sector 5 is defective on head 0 in cylinder 0.
2
1
Index
Head 0
Defective
sector
If an access request to sector 5 is specified, the device accesses physical sector 6 instead of sector 5.
Sector (logical)
Sector (physical)
Cylinder 0
4
3
6
5
297
300
299
298
8
7
2
1
4
3
6
5
7
299
298
Figure 6.7
Sector slip processing