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
.
Note
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, follow the procedure described in Preparing a volume for DRL and instant snapshots.
If the volume was created before release 4.0 of VxVM, and has any attached snapshot plexes, or is associated with any snapshot volumes, follow the procedure given in Upgrading existing volumes to use version 20 DCOs.
# 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:
# vxsnap -g
volumedg -b addmir
volume mirvol=
snapvol
\
snapvoldg
mirdg=
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
\
mirdg=snapvoldg
Note 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:
# vxsnap -g dbasedg make \
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.
When you want to resynchronize the snapshot volume' s data with the primary database, you can refresh the snapshot plexes from the original volume as described below:
# vxsnap -g
snapvoldg
reattach
snapvol
source=
vol \
volumedg
sourcedg=
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:
You can then resume the procedure from step 6.