The version 0 data change object (DCO) and DCO volume layout was introduced in VxVM 3.2. The version 0 layout supports traditional (third-mirror) snapshots, but not full-sized instant snapshots, space-optimized instant snapshots nor DRL configured within the DCO volume.
You need a license to use the Persistent FastResync feature. If you do not have a license, you can configure a DCO object and DCO volume so that snap objects are associated with the original and snapshot volumes. However, without a license, only full resynchronization can be performed.
To create a volume with an attached version 0 DCO object and volume
# vxdg list diskgroup
# vxdg upgrade diskgroup
# vxassist [-g diskgroup] make volume length layout=layout \ logtype=dco [ndcomirror=number] [dcolen=size] \ [fastresync=on] [other attributes]
For non-layered volumes, the default number of plexes in the mirrored DCO volume is equal to the lesser of the number of plexes in the data volume or 2. For layered volumes, the default number of DCO plexes is always 2. If required, use the ndcomirror attribute to specify a different number. It is recommended that you configure as many DCO plexes as there are data plexes in the volume. For example, specify ndcomirror=3 when creating a 3-way mirrored volume.
The default size of each plex is 132 blocks unless you use the dcolen attribute to specify a different size. If specified, the size of the plex must be a multiple of 33 blocks from 33 up to a maximum of 2112 blocks.
By default, FastResync is not enabled on newly created volumes. Specify the fastresync=on attribute if you want to enable FastResync on the volume. If a DCO object and DCO volume are associated with the volume, Persistent FastResync is enabled; otherwise, Non-Persistent FastResync is enabled.
# vxvol [-g diskgroup] set logtype=drl|drlseq volume
If you use ordered allocation when creating a mirrored volume on specified storage, you can use the optional logdisk attribute to specify on which disks dedicated log plexes should be created. Use the following form of the vxassist command to specify the disks from which space for the logs is to be allocated:
# vxassist [-g diskgroup] -o ordered make volume length \ layout=mirror logtype=log_type logdisk=disk[,disk,...] \ storage_attributes