Fujitsu MPG3xxxAT, Product Manual

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C141-E110-02EN 6 - 11
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.
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
795
798 797 796 8 7
2 1 4 3 6 5 7 797 796
Figure 6.7 Sector slip processing
unused