Fujitsu MHN2100AT - Mobile 10 GB Hard Drive, Product Manual

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6.4 Read-Ahead Cache
C141-E120-02EN 6-11
Notes:
1) 4 alternate cylinders are provided for each head in zone 14 (inner
side).
2) When an access request to logical sector 4 is specified, the device
accesses the alternated sector in the alternate cylinder instead of
sector 4. When an access request to sectors next to logical sector 5
is specified, the device seeks to cylinder 0, head 0, and continues the
processing.
Figure 6.6 Alternate cylinder assignment
(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.
An unrecoverable write error occurs during write error retry, automatic alternate
assignment is performed.
6.4 Read-Ahead Cache
After read command which involves read data from the disk medium is
completed, the read-ahead cache function reads the subsequent data blocks
automatically and stores the data to the data buffer.
0 1 2 3 4 5 6 658 659
0 1 2 3 4 5 6 658 659 (unused)
Index
Sector (Physical)
Sector (Logical)
Already
assigned
Defective sector is assigned to unassigned sector.
Cylinder 0
Head 0
Alternate
cylinder
Head 0
Defective
sector