Physical Database Integrity
Physical database integrity checking mechanisms usually detect data corruption caused by lost writes or bit, byte, and byte string errors. Most hardware devices protect against data corruption automatically by means of various error detection and correction algorithms. For example, bit‑ and byte‑level corruption of disk I/O is usually detected, and often corrected, by error checking and correcting mechanisms at the level of the disk drive hardware, and if the corruption is detected but cannot be corrected, the pending I/O request fails.
Similarly, bit‑ and byte‑level corruption of an I/O in transit might be detected by various parity or error checking and correcting mechanisms in memory and at each intermediate communication link in the path. Again, if the corruption is detected, but cannot be corrected, the pending I/O request fails.