Tuesday, January 18, 2011

Checksum vs Torn Page Detection

Torn Page Detection
Writes a bit for every 512 bytes in the page
  • Detects when a page was not successfully written to disk
  • Does not detect if all bytes were written accurately
Checksum
Calculates a checksum value before passing data to the IO system (which then writes data to the disk).
  • Guarantees that SQL Server had no part in corrupting the page.
  • Detects corruption (by IO system) when page is read from disk.
  • Checksum error (824) will be generated if data differs.

Ref : Whats best: Torn Page Detection or Checksum?


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