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6.4.1
Spare area
Following two types of spare area are provided in the user space.
1) Spare sector for sector slip:
used for alternating defective sectors at formatting in shipment (128 sectors/32 cylinders)
2) Spare cylinder for alternative assignment:
used by automatic alternative assignment. (4 cylinder/drive)
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
unused
Figure 6.7
Sector slip processing
C141-E110-03EN
7
8
796
6
7
795
797
798
796
797
6 - 11
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