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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 in case that a physical track
contains one or two defective sectors (2 sectors/track)
2) Spare cylinder for alternative assignment:
used for alternative assignment for the third and subsequent defective sectors in case that a
physical track contains three or more defective sectors, and also used by automatic
alternative assignment. (1 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-E072-01EN
406
7
8
298
6
7
405
297
407
408
299
300
SP
406
298
299
6 - 11
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