DRL Dirty Region Logging

A VxVM mechanism that tracks mirror write inconsistency, which helps in fast resynchronization of mirrors after system crash. Internally, DRL is implemented as a map and not as a log.

The method by which the VxVM monitors and logs modifications to a plex as a bitmap of changed regions. For volumes with a new-style DCO volume, the dirty region log is maintained in the DCO volume. Otherwise, the dirty region log is allocated to an associated subdisk called a log subdisk.

An optional property of a volume, used to provide a speedy recovery of mirrored volumes after a system failure. DRL keeps track of the regions that have changed due to I/O writes to a mirrored volume.