Abstract: Where a number n of read attempts are required to successfully read a data sector, with the first n-1 attempts returning a disk drive read error, the number of attempts required is compared to a predefined threshold selected to indicate that the sector is unreliable and is in danger of becoming completely unrecoverable. If the threshold number of attempts is not exceeded, the sector is presumed to still be good and no further action need be taken. If the threshold number of attempts was equaled or exceeded, however, the unreliable or failing sector is relocated to a reserved replacement sector, with the recovered data written to the replacement sector. The failing data sector is remapped to the replacement sector, which becomes a fully functional substitute for the failing sector for future reads and writes while preserving the original user data. Data within a failing sector is thus preserved before the sector becomes completely unrecoverable.

Abstract: If necessary, problematic sectors are isolated when an attempt to write a group of data blocks to corresponding disk sectors returns a write error by attempting to write each data sector individually, registering each individual sector which returns a write error for separate, further examination. Since disk drive vendors do not employ consistent write error messages in device drivers, true write faults—those caused by failure of disk media such that a sector becomes unreliable or unrecoverable—are then identified by an operating system device manager for the disk drive by writing the data block to a reserved replacement sector and monitoring the status of that write. If the write to the replacement sector also fails with a write error, the error signaled likely indicates a true drive status and an appropriate error is returned to the file system which issued the write request. If the write to the replacement sector succeeds, however, the write error most likely reflects a failing sector.

Abstract: Where a number n of read attempts are required to successfully read a data sector, with the first n−1 attempts returning a disk drive read error, the number of attempts required is compared to a predefined threshold selected to indicate that the sector is unreliable and is in danger of becoming completely unrecoverable. If the threshold number of attempts is not exceeded, the sector is presumed to still be good and no further action need be taken. If the threshold number of attempts was equaled or exceeded, however, the unreliable or failing sector is relocated to a reserved replacement sector, with the recovered data written to the replacement sector. The failing data sector is remapped to the replacement sector, which becomes a fully functional substitute for the failing sector for future reads and writes while preserving the original user data. Data within a failing sector is thus preserved before the sector becomes completely unrecoverable.

Abstract: When a read to a disk returns an error for a sector previously identified as good, the read is retried a predetermined number of times to attempt to recover the sector data. If the sector is unrecoverable, the failed sector is relocated and an “unusable” bit associated with the replacement sector is set to indicate that the data is bad. The unusable bit indicates that the replacement sector is good, but the data contained within the replacement sector is bad. A read error is generated for subsequent reads to the replacement sector as long as the unusable bit remains set. The unusable bit is cleared after a write to or reformat of the replacement sector. The replacement sector thereafter becomes a fully functional substitute for the failed sector, containing good data. The validity of data within the replacement sector is identified at all times, allowing use of bad data to be avoided.

Abstract: Where a number n of read attempts are required to successfully read a data sector, with the first n-1 attempts returning a disk drive read error, the number of attempts required is compared to a predefined threshold selected to indicate that the sector is unreliable and is in danger of becoming completely unrecoverable. If the threshold number of attempts is not exceeded, the sector is presumed to still be good and no further action need be taken. If the threshold number of attempts was equaled or exceeded, however, the unreliable or failing sector is relocated to a reserved replacement sector, with the recovered data written to the replacement sector. The failing data sector is remapped to the replacement sector, which becomes a fully functional substitute for the failing sector for future reads and writes while preserving the original user data. Data within a failing sector is thus preserved before the sector becomes completely unrecoverable.

Abstract: When a read to a disk returns an error for a sector previously identified as good, the read is retried a predetermined number of times to attempt to recover the sector data. If the sector is unrecoverable, the failed sector is relocated and an “unusable” bit associated with the replacement sector is set to indicate that the data is bad. The unusable bit indicates that the replacement sector is good, but the data contained within the replacement sector is bad. A read error is generated for subsequent reads to the replacement sector as long as the unusable bit remains set. The unusable bit is cleared after a write to or reformat of the replacement sector. The replacement sector thereafter becomes a fully functional substitute for the failed sector, containing good data. The validity of data within the replacement sector is identified at all times, allowing use of bad data to be avoided.