This section describes a procedure for implementing off-host decision support for a volume in a private disk group. The intention is to present an outline of how to set up a replica database. It is beyond the scope of this guide to describe how to configure a database to use this procedure.
To set up a replica database using the table files that are configured within a volume in a private disk group
# vxprint -g
volumedg -F%instant
volume
This command returns on
if the volume can be used for instant snapshot operations; otherwise, it returns off
.
If the volume was created under VxVM 4.0 or a later release, and it is not associated with a new-style DCO object and DCO volume, it must be prepared.
See "Preparing a volume for DRL and instant snapshots" on page 285.
If the volume was created before release 4.0 of VxVM, and has any attached snapshot plexes, or is associated with any snapshot volumes, it must be upgraded.
See "Upgrading existing volumes to use version 20 DCOs" on page 289.
# vxprint -g
volumedg -F%fastresync
volume
This command returns on
if FastResync is enabled; otherwise, it returns off
.
If FastResync is disabled, enable it using the following command on the primary host:
See "Creating a volume for use as a full-sized instant or linked break-off snapshot" on page 331.
It is recommended that a snapshot disk group is dedicated to maintaining only those disks that are used for off-host processing.
# vxsnap -g
volumedg -b addmir
volume mirvol=
snapvol
\
You can use the vxsnap
snapwait
command to wait for synchronization of the linked snapshot volume to complete:
# vxsnap -g
volumedg snapwait
volume mirvol=
snapvol
\
This step sets up the snapshot volumes, and starts tracking changes to the original volumes.
When you are ready to create a replica database, proceed to step 6.
source=
volume
/snapvol=
snapvol
/snapdg=
snapvoldg
If a database spans more than one volume, you can specify all the volumes and their snapshot volumes using one command, as shown in this example:
source=vol1/snapvol=snapvol1/snapdg=sdg \
source=vol2/snapvol=snapvol2/snapdg=sdg \
source=vol3/snapvol=snapvol3/snapdg=sdg
This step sets up the snapshot volumes ready for the backup cycle, and starts tracking changes to the original volumes.
At a later time, you can resynchronize the snapshot volume' s data with the primary database.
To refresh the snapshot plexes from the original volume
# vxsnap -g
snapvoldg
reattach
snapvol
source=
vol \
For example, to reattach the snapshot volumes svol1
, svol2
and svol3
:
# vxsnap -g sdg reattach svol1 \
source=vol1 sourcedg=dbasedg \
svol2 source=vol2 sourcedg=dbasedg \
svol3 source=vol3 sourcedg=dbasedg
You can use the vxsnap
snapwait
command to wait for synchronization of the linked snapshot volume to complete:
# vxsnap -g
volumedg snapwait
volume mirvol=
snapvol
You can then resume the procedure from step 6.