in the Aries recovery algorithm: – Analysis: Scan the log forward (from the most recent checkpoint) to iden8fy all Xacts that were ac8ve, and all dirty pages in the buffer pool at the 8me of the crash. – Redo: Redoes all updates to dirty pages in the buffer pool, as needed, to ensure that all logged updates are in fact carried out and wricen to disk. – Undo: The writes of all Xacts that were ac8ve at the crash are undone (by restoring the before value of the update, which is in the log record for the update), working backwards in the log. (Some care must be taken to handle the case of a crash occurring during the recovery process!) Lipyeow Lim -‐-‐ University of Hawaii at Manoa 10