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Creating a volume with dirty region logging enabled

Dirty region logging (DRL), if enabled, speeds recovery of mirrored volumes after a system crash. To enable DRL on a volume that is created within a disk group with a version number between 20 and 100, specify the logtype=drl attribute to the vxassist make command as shown in this example usage:

# vxassist [-g diskgroup] make volume length layout=layout \

  logtype=drl [nlog=n] [loglen=size] [other attributes]

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 create a mirrored 10GB volume, vol02, with two log plexes in the disk group, mydg, use the following command:

# vxassist -g mydg make vol02 10g layout=mirror logtype=drl \

  nlog=2 nmirror=2

Sequential DRL limits the number of dirty regions for volumes that are written to sequentially, such as database replay logs. To enable sequential DRL on a volume that is created within a disk group with a version number between 70 and 100, specify the logtype=drlseq attribute to the vxassist make command.

# vxassist [-g diskgroup] make volume length layout=layout \

  logtype=drlseq [nlog=n] [other attributes]

It is also possible to enable the use of Persistent FastResync with this volume.

See "Creating a volume with a version 0 DCO volume" on page 244.


  Note   Operations on traditional DRL log plexes are usually applicable to volumes that are created in disk groups with a version number of less than 110. If you enable DRL or sequential DRL on a volume that is created within a disk group with a version number of 110 or greater, the DRL logs are usually created within the plexes of a version 20 DCO volume.


See "Creating a volume with a version 20 DCO volume" on page 245.