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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.
Index
Sector (physical)
1
2
Cylinder 0
Head 0
1
2
Sector (logical)
If an access request to sector 5 is specified, the device accesses physical sector 6 instead of sector 5.
3
4
5
6
Defective
sector
3
4
5
Figure 6.7
Sector slip processing
C141-E055-01EN
334
7
8
298
333
6
7
297
335
336
299
300
334
335
298
299
6 - 11
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