Figure 6.8 Alternate Cylinder Assignment - Fujitsu MHM2100AT - Mobile 10 GB Hard Drive Product Manual

(2) Alternate cylinder assignment
A defective sector is assigned to the spare sector in the alternate cylinder.
This processing is performed when the alternate assignment is specified in the
FORMAT TRACK command or when the automatic alternate processing is
performed at read error occurrence.
Figure 6.8 shows an example where (physical) sector 5 is detective on head 0 in
cylinder 0.
Index
Sector (Physical)
1
Cylinder 0
Head 0
1
Sector (Logical)
Alternate
cylinder
Head 0
Defective sector is assigned to unassigned sector.
Notes:
(3) Automatic alternate assignment
The device performs the automatic alternate assignment when ECC correction
performance is increased during read error retry, a read error is recovered. Before
automatic alternate assignment, the device performs rewriting the corrected data
to the erred sector and rereading. If no error occurs at rereading, the automatic
alternate assignment is not performed.
C141-E104-03EN
2 3 4 5
Defective
sector
2 3 4 (unused) 5
Already
assigned
1) 4 alternate cylinders are provided for each head in zone 14 (inner
side).
2) When an access request to physical sector 5 is specified, the device
accesses the alternated sector in the alternate cylinder instead of
sector 5. When an access request to sectors next to sector 5 is
specified, the device seeks to cylinder 0, head 0, and continues the
processing.

Figure 6.8 Alternate cylinder assignment

6.4 Defect Management
6 7
6 7
505 506
505 506
6-13