Creating volumes 253

Creating a striped 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 [-gdiskgroup] 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 [-gdiskgroup] 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” on page 250.

Creating a striped volume

A striped volume contains at least one plex that consists of two or more subdisks located on two or more physical disks. For more information on striping, see “Striping (RAID-0)” on page 38.

Note: A striped volume requires space to be available on at least as many disks in the disk group as the number of columns in the volume.

To create a striped volume, use the following command:#vxassist [-b] [-g diskgroup] make volume length layout=stripe

For example, to create the 10-gigabyte striped volume volzebra, in the disk group, mydg, use the following command:

# vxassist -b -g mydg make volzebra 10g layout=stripe

This creates a striped volume with the default stripe unit size (64 kilobytes) and the default number of stripes (2).