VERITAS Volume Manager 3.1 Migration Guide

Converting LVM to VxVM
Converting LVM Volume Groups to VxVM Disk Groups
Chapter 2 33
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.
A 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
This file provides information on how to proceed further to link the old
LVM volume names to the new VxVM device names.
CAUTION This method of resolving the naming problem has risks. The symbolic
links can become stale. For example, if a database refers to
/dev/vx/rdsk/vol1 through a symbolic link /dev/vg00/rvol1(“the old
LVM name)”, and if the underlying VxVM volume configuration is