VERITAS Volume Manager 4.1 Administrator's Guide

Conﬁguring Off-Host Processing

Implementing Off-Host Processing Solutions

Chapter 11392

If you start vxassist snapstart in the background using the -b option,

you can use the vxassist snapwait command to wait for the creation of

the mirror to complete as shown here:

# vxassist -g volumedg snapwait volume

If vxassist snapstart is not run in the background, it does not exit

until the mirror has been synchronized with the volume. The mirror is

then ready to be used as a plex of a snapshot volume. While attached to

the original volume, its contents continue to be updated until you take

the snapshot.

Use the nmirror attribute to create as many snapshot mirrors as you

need for the snapshot volume. For applications where data redundancy is

required for the volume that contains the replica database, specify a

number greater than one.

Step 4. Prepare the OHP host to receive the snapshot volume that contains the

copy of the database tables. This may involve setting up private volumes

to contain any redo logs, and conﬁguring any ﬁles that are used to

initialize the database.

Step 5. On the primary host, suspend updates to the volume that contains the

database tables. The database may have a hot backup mode that allows

you to do this by temporarily suspending writes to its tables.

Step 6. On the primary host, make a snapshot volume, snapvol, using the

following command:

# vxassist -g volumedg snapshot [nmirrors=N] volume snapvol

If required, use the nmirrors attribute to specify the number of mirrors

in the snapshot volume.

If a database spans more than one volume, specify all the volumes and

their snapshot volumes on the same line, for example:

# vxassist -g dbasedg snapshot vol1 snapvol1 vol2 snapvol2 \

vol3 snapvol3

Step 7. On the primary host, release the tables from hot backup mode.

Step 8. On the primary host, use the following command to split the snapshot

volume into a separate disk group, snapvoldg, from the original disk

group, volumedg:

# vxdg split volumedg snapvoldg snapvol