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Message Posted: Fri, 23 Oct 2004 @ 00:45:20 GMT

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One way the DBMS can recover from and correct a detected integrity error is via Fallback. The file system has always has some basic integrity checks, but the checksum enhances that capability. When a data corruption occurs, the amp goes fatal and the system restarts in fallback mode. The failing hardware is repaired and then the data can be corrected with a rebuild from fallback

There are many mechanisms in the database for prevention, detection, correction, and recovery from data corruption. The checksum feature provides prevention and detection mechanisms. Prevention, because when checksum is enabled on a table no blocks in that table are ever updated in place on disk. In that way the old copy of the block is always available for recovery.

Mark

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