Two-Level Sector Reallocation
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-28
Previously, two distinct methods of handling bad sectors on disks have been used. The first method placed the responsibility in the host computer using the disk drive. If a bad sector should be encountered, it was the job of the controlling software to take recovery action, and then, if required, move data to some other address on the disk. The second method moved the bad sector management to an "intelligent" drive. One typical feature of these disk drives is that the drive includes some "spare" sectors--possibly one or more for each track. A "reassign" command can be issued to the disk and this command will result in some "logical" disk address being moved to another physical location on the disk. This reassignment by the drive involves no further work or bookkeeping by the disk-controlling software.