Crash Recovery: Big Picture

• Start from a checkpoint (found via master record).

• Three phases. Need to:
  • Figure out which Xacts committed since checkpoint, which failed (Analysis).
  • REDO all actions.
    • (repeat history)
  • UNDO effects of failed Xacts.

Oldest log rec. of Xact active at crash

Smallest recLSN in dirty page table after Analysis

Last chkpt

CRASH

A

R

U

Previous slide

Next slide

Back to first slide

View graphic version