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.
2) When a write error occurs and the error does not recovered.
Figure 6.9 shows an example where (physical) sector 5 is automatic alternated on head 0 in cylinder 0.
Index
Cylinder 0
Head 0
Alternate cylinder
Head 0
Sector (physical) |
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1 | 2 |
| 3 | 4 | 5 |
| 6 | 7 | ||
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| Defective |
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1 | 2 |
| 3 | 4 | (unused) | 6 | 7 | |||
Sector (logical) |
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Already assigned
Defective sector is assigned to unassigned sector.
24299 300243
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| SP |
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242 300299243
14 alternatecylinders areis providedinforoutereach sidehead. in zone 13 (inner side).
When an access request to 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 6.9 Automatic Alternate assignment
6 - 13 |
