Fujitsu MHM2150AT Manual/User Guide - Page 212
Alternate cylinder assignment, If no error occurs at rereading, the automatic
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6.4 Defect Management (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 2 3 4 5 6 7 Cylinder 0 Defective sector Head 0 1 2 3 4 (unu5sed) 6 7 Sector (Logical) Alternate cylinder Head 0 Already assigned Defective sector is assigned to unassigned sector. 505 506 505 506 Notes: 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 (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 6-13