The next step is to start the mirroring process. We used the vxassist command to transform the Storage volume from a simple, concatenated volume into a mirrored volume. Optionally, a DRL (Dirty Region Log) can be added to the volume. If enabled, the DRL speeds recovery of mirrored volumes after a system crash. It requires an additional 1 Megabyte of extra disk space.

For more information about DRL logging,:

See the Symantec Storage Foundation Administrator's Guide