VERITAS Volume Manager 4.1 Administrator's Guide

Administering Volumes
Enabling FastResync on a Volume
Chapter 8298
Enabling FastResync on a Volume
NOTE You may need an additional license to use this feature.
FastResync performs quick and efficient resynchronization of stale
mirrors. It also increases the efficiency of the VxVM snapshot
mechanism when used with operations such as backup and decision
support. See “Backing Up Volumes Online Using Snapshots” on page 308
and “FastResync” on page 52 for more information.
From Release 3.2, there are two possible versions of FastResync that can
be enabled on a volume:
• Persistent FastResync, introduced in VxVM 3.2, holds copies of the
FastResync maps on disk. These can be used for the speedy recovery
of mirrored volumes if a system is rebooted. This form of FastResync
requires that both a data change object (DCO) and DCO volume first
be associated with the volume.
See “Creating a Volume with a DCO and DCO Volume” on page 243,
and “Adding a DCO and DCO Volume” on page 277 for more
information.
If the existing volume was created before release 3.2 of VxVM, and it
has any attached snapshot plexes or it is associated with any
snapshot volumes, follow the procedure given in “Enabling
Persistent FastResync on Existing Volumes with Associated
Snapshots” on page 302.
• Non-Persistent FastResync, introduced in VxVM 3.1, holds the
FastResync maps in memory. These do not survive on a system that
is rebooted.
By default, FastResync is not enabled on newly created volumes. Specify
the fastresync=on attribute to the vxassist make command if you want to
enable FastResync on a volume that you are creating.