VERITAS Volume Manager 3.5 Migration Guide (August 2002)

Converting LVM Volume Groups to VxVM Disk Groups Final 24 July 2002
18 VERITAS Volume Manager Migration Guide
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 changed in any way, the database
could refer to a missing or different volume.
Note You may want to use this symbolic link approach to ease the transition to VxVM.
You can set up the symbolic links after the successful conversion to VxVM. Then,
you can do the investigation on a case by case basis for each volume. Once you are
satisfied that there are no problems introduced by the name change, the symbolic
link to that volume can be removed. You must be careful to maintain a static VxVM
volume configuration during this transition period.
Over time, the ultimate goal should be that the underlying VxVM naming is used by all
applications, and that there are no indirect references to those volumes.
6. Stopping application access to volumes in the volume group to be converted
No applications can be active on the LVM volume group undergoing conversion. Before
attempting to convert any volume group, you must ensure that applications using that
group are down. This involves stopping databases, unmounting file systems, etc.
Note If you are converting a volume with swap space on it, the conversion requires a
reboot. The swap space cannot be taken out of control of the operating system with
a shutdown to single user mode.
As described in “Conversion and Reboot” on page 19, vxvmconvert tries to unmount
mounted file systems during the conversion. Bear in mind though, that vxvmconvert
makes no attempt to close down running applications on those file systems, nor does it
attempt to deal with applications (e.g., databases) running on raw LVM volumes.
Note It is strongly recommended that you do not rely on vxvmconvert's mechanisms
for unmounting file systems. Conversion will be simpler if you close applications,
and unmount file systems before running vxvmconvert.
To unmount a file system, use the following command:
# umount file-system