VERITAS Volume Manager 3.5 Release Notes (August 2003)

VERITAS Volume Manager™ HP-UX 11i v2 Release Notes
Patches and Fixes in This Version
Chapter 1 33
Workaround: Allow X server access by typing:
xhost + [hostname]
Volume Manager and Multi-Host Failover Configurations
Outside the context of clustering functionality, Volume Manager disk
groups can be imported (made available) from only one host at any given
time. When a host imports a disk group as private, the volumes and
configuration of that disk group becomes accessible to the host. If the
administrator or system software wants to privately use the same disk
group from another host, the host that already has the disk group
imported (importing host) must deport (give up access to) the disk group.
Once deported, the disk group can be imported by another host.
If two hosts are allowed to access a disk group concurrently without
proper synchronization, such as that provided by the Oracle Parallel
Server, the configuration of the disk group, and possibly the contents of
volumes, can be corrupted. Similar corruption can also occur if a file
system or database on a raw disk partition is accessed concurrently by
two hosts, so this is not a problem limited to Volume Manager.
Import Lock When a host in a non-clustered environment imports a
disk group, an import lock is written on all disks in that disk group. The
import lock is cleared when the host deports the disk group. The
presence of the import lock prevents other hosts from importing the disk
group until the importing host has deported the disk group.
Specifically, when a host imports a disk group, the import normally fails
if any disks within the disk group appear to be locked by another host.
This allows automatic re-importing of disk groups after a reboot
(autoimporting) and prevents imports by another host, even while the
first host is shut down. If the importing host is shut down without
deporting the disk group, the disk group can only be imported by another
host by clearing the host ID lock first (discussed later).
The import lock contains a host ID (in Volume Manager, this is the host
name) reference to identify the importing host and enforce the lock.
Problems can therefore arise if two hosts have the same host ID.