Veritas Volume Manager 5.0 Administrator's Guide (September 2006)

406 Administering cluster functionality
Multiple host failover configurations
Note: Since Veritas Volume Manager uses the host name as the host ID (by default), it is
advisable to change the host name of one machine if another machine shares its host name.
To change the host name, use the vxdctl hostid new_hostname command.
Failover
The import locking scheme works well in an environment where disk groups are not
normally shifted from one system to another. However, consider a setup where two hosts,
Node A and Node B, can access the drives of a disk group. The disk group is first imported
by Node A, but if Node B detects that Node A has crashed or shut down, Node B imports
(fails over) the disk group to provide access to the volumes.
Veritas Volume Manager can support failover, but it relies on Serviceguard setup to
ensure that the first system is shut down or unavailable before the disk group is imported
to another system.
Corruption of disk group configuration
If vxdg import is used with -C (clears locks) and/or -f (forces import) to import a disk
group that is still in use from another host, disk group configuration corruption is likely to
occur. Volume content corruption is also likely if a file system or database is started on the
imported volumes before the other host crashes or shuts down.
If this kind of corruption occurs, you must probably rebuild your configuration from
scratch and reload all volumes in the disk group from a backup. To backup and rebuild the
configuration, if nothing has changed, use
vxprint -mspvd and store the output which
can be fed to
vxmake to restore the layouts. There are typically numerous configuration
copies for each disk group, but corruption nearly always affects all configuration copies,
so redundancy does not help in this case.
Disk group configuration corruption usually shows up as missing or duplicate records in
the configuration databases. This can result in a variety of vxconfigd error messages
VxVM vxconfigd ERROR V-5-1-569 Disk group group,Disk disk:Cannot auto-
import group: reason
where the reason can describe errors such as:
Association not resolved
Association count is incorrect
Duplicate record in configuration
Configuration records are inconsistent
These errors are typically reported in association with specific disk group configuration
copies, but usually apply to all copies. The following is usually displayed along with the
error:
Disk group has no valid configuration copies