Veritas Volume Manager 5.0 Migration Guide, HP-UX 11i v3, First Edition, May 2008

24 Converting LVM to VxVM
Converting LVM volume groups to VxVM disk groups
Non-file system back up
If a logical volume you are converting does not contain a file system, and is
being used directly by an application (such as a database application), use the
backup facilities provided by the application. If no such facility exists, consider
using the
dd command.
5. Planning for new VxVM logical volume names
When you change from LVM volumes to VxVM volumes, the device names by
which your system accesses data are changed. LVM creates device nodes for its
logical volumes in
/dev under directories named for the volume group. VxVM
creates its device nodes in
/dev/vx/dsk and /dev/vx/rdsk. When conversion is
complete, the old LVM device nodes are gone from the system, and the system
will access data on the device nodes in
/dev/vx.
This change in names can present problems. Any application that refers to
specific device node names will be at risk when these names change. Similarly,
any files that record specific device node names for use by applications can be
problematic.
The most obvious area where this problem arises is in
/etc/fstab. To handle
this problem,
vxvmconvert will rewrite the fstab with the new VxVM names
when conversion is done so that
fsck, mount, and related utilities will behave as
they did prior to the conversion.
There are potentially many other applications, though, that may be put at risk
by the name changes in conversion.
vxvmconvert cannot help with these. The
system administrator must examine the mechanisms used in each of the
following areas to see if they reference LVM device names:
■ Databases run on raw logical devices may record the name of that device
node.
■ Backup systems may do device level backups based on device node names
recorded in private files. Also labeling of the backups may record device
names.
■ Scripts run by cron(1M).
■ Other administrative scripts.
Workaround
vxvmconvert records a mapping between the names of the LVM device nodes
and VxVM device nodes. This data can be used to create symbolic links from the
old LVM volume to the new VxVM device names. The mapping is recorded in the
file:
/etc/vx/reconfig.d/vgrecords/vol_grp_name/vol_grp_name.trans