VERITAS Volume Manager 3.5 Administrator's Guide (September 2002)

Chapter 8, Administering Volumes

Disabling FastResync

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Disabling FastResync

Use the vxvol command to turn off Persistent or Non-Persistent FastResync for an

existing volume, as shown here:

# vxvol [-g diskgroup] set fastresync=off volume

Turning FastResyncoffreleasesall tracking mapsforthe speciﬁed volume.Allsubsequent

reattaches will not use the FastResync facility, but perform a full resynchronization of the

volume. This occurs even if FastResync is later turned on.

Enabling Persistent FastResync on Existing Volumes with

Associated Snapshots

The procedure described in this section describes how to enable Persistent FastResync on

a volume created before release 3.2 of VxVM, and which has attached snapshot plexes or

is associated with one or more snapshot volumes.

Note If you do not perform the reconﬁguration described in this section, full

resynchronization is required every time that snapback is used to reattach a

snapshot to its original volume.

If a volume was created before release 3.2 of VxVM, but does not have any snapshot

plexes or associated snapshot volumes, you do not need to perform this procedure if you

perform a snapstart operation on the volume after you have added a data change

object (DCO) and DCO volume to it.

Before enabling Persistent FastResync on an existing volume that contains any snapshot

plexes, or which has any snapshot volumes, you must create and associate a data change

object (DCO) and DCO volume with the volume. The number of plexes that you need to

conﬁgurein aDCO volumeis determined by the number of data and snapshot plexes that

must be tracked. (A volume’s snapshot plexes are those that the vxprint command

displays with their state set to SNAPDONE.)

Because Persistent FastResync performs tracking on the original volume and on its

snapshot volumes, you must also conﬁgure and associate a DCO and DCO volume with

each snapshot volume. It is only necessary to do this before you have enabled Persistent

FastResync on a volume. Once you have enabled Persistent FastResync on a volume, the

snapstart, snapshot and snapback operations handle the creation and management

of DCOs and DCO volumes automatically.