The recommended method for enabling FastResync on a volume with a version 20 DCO is to use the vxsnap prepare command.
FastResync quickly and efficiently resynchronizes stale mirrors. When you use FastResync with operations such as backup and decision support, it also increases the efficiency of the VxVM snapshot mechanism.
You can enable the following versions of FastResync on a volume:
Persistent FastResync holds copies of the FastResync maps on disk. If a system is rebooted, you can use these copies to quickly recover mirrored volumes. To use this form of FastResync, you must first associate a version 0 or a version 20 data change object (DCO) and DCO volume with the volume.
Non-Persistent FastResync holds the FastResync maps in memory. These maps do not survive on a system that is rebooted.
By default, FastResync is not enabled on newly-created volumes. If you want to enable FastResync on a volume that you create, specify the fastresync=on attribute to the vxassist make command.
Note: |
You cannot configure Persistent and Non-Persistent FastResync on a volume. If a DCO is associated with the volume, Persistent FastResync is used. Otherwise, Non-Persistent FastResync is used. |
To turn on FastResync for an existing volume, specify fastresync=on to the vxvol command as follows:
# vxvol [-g diskgroup] set fastresync=on volume
To use FastResync with a snapshot, you must enable FastResync before the snapshot is taken, and it must remain enabled until after the snapback is completed.