Caution:  If the existing volume was created before the release of VxVM 3.2 and it has any attached snapshot plexes or it is associated with any snapshot volumes, you will need to convert the volume to Persistent FastResync.

This document applies to existing volumes without snapshot plexes or associated snapshot volumes.

To put Persistent FastResync into effect for a volume, a DCO object and DCO log volume must first be associated with that volume.

Note:  You may need an additional license to use the Persistent FastResync feature.


Even if you do not have a license, you can configure a DCO object and DCO log volume so that snap objects are associated with the original and snapshot volumes.


How to add a DCO object and DCO log volume to an existing volume   

Note: It does not matter if the volume already has Dirty Region Logging (DRL) enabled.

1. Ensure that the disk group containing the existing volume has been upgraded to at least version90. Use the following command to check the version of a diskgroup:

# vxdg list

To upgrade a disk group to the latest version, usethe following command:

# vxdg upgrade


2. If FastResync has been turned on for that volume, non-persistent FastResync has been enabled.


To turn on persistent FastResync, the attribute fastresync has to be disabled first.


The following example illustrates the error you may get as a result of FastResync being enabled:

#vxassist -g addlog vol400 logtype=dco

vxvm:vxassist: ERROR:Volume vol400 already has Non-Persistent FastResyncEnabled

Use the following command to switch fastresyncoff:

# vxvol -g set fastresync=off vol400

3. Use the following command to add a DCO and DCO log volume to the existing volume:

# vxassist -g addlog logtype=dco [ndcolog=number][dcologlen=size]


#vxassist -g addlog logtype=dco


Example


To add a DCO object and DCO log volume with a plex size of 66 blocks to the volume "vol400" in the disk group named vm32dg, type:

# vxassist -g vm32dg addlog vol400 logtype=dco dcologlen=66


To view the details of the DCO object and DCO log volume that are associated with a volume,use the vxprint command.


The following is an example vxprint output for the volume named vol400 (the TUTIL0 and PUTIL0 columns are omitted for clarity). In this output, the DCO object is shown as vol400_dco, and the DCO log volume as vol400_dcl with 2 plexes, vol400_dcl-01andvol400_dcl-02.


 

For more information, see the vxassist manual page.