Creating a Volume with Dirty Region Logging Enabled

Note The procedure in this section is applicable to volumes that are created in disk groups with a version number of less than 110. To enable DRL or sequential DRL on a volume that is created within a disk group with a version number of 110 or greater, follow the procedure described in Creating a Volume with a Version 20 DCO Volume, which creates the DRL logs within the plexes of a version 20 DCO volume.

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]

Note If you also want to allow the use of Persistent FastResync with the volume, use the procedure described in Creating a Volume with a Version 0 DCO Volume.


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Product: Volume Manager Guides
Manual: Volume Manager 4.1 Administrator's Guide
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