The primary purpose of RAID-5 logging is to quickly reactivate a RAID-5 volume when a system is restarted following a crash. Without RAID-5 logging enabled, a time-consuming reactivation of the entire RAID-5 volume is necessary.

When a RAID-5 log is created, a log subdisk is added to the volume. Multiple RAID-5 logs can be associated with a single RAID-5 volume as a fault-tolerant measure. Depending on the number of logs configured, this may result in degraded performance. If more than one log is added, then the logs are just mirrored. DRL logs for RAID volumes are called RAID-5 logs and provide the same functionality.

If a RAID-5 log is available, updates need to be made only to the data and parity portions of the volume that were in transit during a system crash. The entire volume does not have to be resynchronized.

A log can be created when the volume is created or can be added later.