Improving Recovery Prefetch

The look-ahead size for prefetching pages of the recovery scan processes can be optimized using the recovery prefetch size configuration parameter.

Boot time, load database, and load tran recovery can prefetch to-be-recovered data pages from disk into cache so that recovery does not need to wait when attempting to redo or undo log records.

Prefetching pages is done by having an auxiliary process operate ahead of the recovery redo or undo scan reading data (and index) pages from disk into cache. Problems can occur if the prefetch auxiliary process:

The look-ahead size can be optimized using the recovery prefetch size configuration parameter. The look-ahead size can be set to be dynamically determined, or you can specify the exact size of the look-ahead in numbers of log records using the recovery prefetch size configuration size parameter.

The settings for recovery prefetch size are: