The Checksum option causes SQL Server to calculate a checksum for a page's content when the content is written to disk. When the page is later read from disk, a checksum is again calculated and compared to the previous value (which was stamped on the page). If the two values do not match, something in the I/O subsystem changed the page and, therefore, the page is corrupt. When an invalid checksum occurs, SQL Server logs an event in the error log and in the Windows Event Log. It is recommended that you monitor SQL Server for these errors (823, 824, and 825).