Adding Traditional DRL Logging to a Mirrored Volume

To put dirty region logging (DRL) into effect for a mirrored volume, a log subdisk must be added to that volume. Only one log subdisk can exist per plex.

To add DRL logs to an existing volume, use the following command:

The nlog attribute can be used to specify the number of log plexes to add. By default, one log plex is added. The loglen attribute specifies the size of the log, where each bit represents one region in the volume. For example, the size of the log would need to be 20K for a 10GB volume with a region size of 64 kilobytes.

For example, to add a single log plex for the volume vol03, in the disk group, mydg, use the following command:

When the vxassist command is used to add a log subdisk to a volume, by default a log plex is also created to contain the log subdisk unless you include the keyword nolog in the layout specification.

For a volume that will be written to sequentially, such as a database log volume, include the logtype=drlseq attribute to specify that sequential DRL is to be used:

Once created, the plex containing a log subdisk can be treated as a regular plex. Data subdisks can be added to the log plex. The log plex and log subdisk can be removed using the procedure described in Removing a Traditional DRL Log.

Removing a Traditional DRL Log

To remove a DRL log, use the vxassist command as follows:

By default, the vxassist command removes one log. Use the optional attribute nlog=n to specify the number of logs that are to remain after the operation completes.

You can use storage attributes to specify the storage from which a log is to be removed. For example, to remove a log on disk mydg10 from volume vol01, enter: