Veritas Volume Manager 5.0.1 Migration Guide, HP-UX 11i v3, First Edition, November 2009

The conversion process involves many steps. Though there are tools to help you
with the conversion, some of these steps cannot be automated. You should be sure
to understand how the whole conversion process works, and what you will need
to do in the process before beginning a volume group conversion.
The tool used for conversion is vxvmconvert. This interactive, menu-driven
program walks you through many of the steps of the process of converting volume
groups for use by VxVM. Using vxvmconvert can reduce the downtime associated
with converting from LVM to VxVM. Without the vxvmconvert tool, the only
possible method of conversion would be to take full backups of user data, destroy
the existing LVM configuration leaving only raw disks, recreate the configuration
in VxVM, and then reload the user data.
The vxvmconvert process converts LVM volume groups to VxVM disk groups in
place. In reality, the utility changes disks within LVM volume groups to VxVM
disks by taking over the areas of the disks used for LVM configuration information,
and creating the equivalent VxVM volume configuration information. User data,
the portions of the disks used for file systems, databases and so on, are not affected
by the conversion.
The act of conversion changes the names by which your system refers to the
logical storage. For this reason, the conversion process is necessarily an off-line
one. There can be no application access to user data in the volume groups
undergoing conversion. Access to the LVM configuration itself (the metadata of
LVM) must also be limited to the conversion process.
Volume group conversion limitations
There are certain LVM volume configurations that cannot be converted to VxVM.
Some of the reasons a conversion could fail are:
■ A volume group with insufficient space for metadata.
In the conversion of LVM to VxVM, the areas of the disks used to store LVM
metadata are overwritten with VxVM metadata. If the VxVM metadata that
needs to be written will not fit the space occupied by the LVM metadata, the
group containing the disk cannot be converted. If you have just enough space
for the conversion, you probably would want to have more space for future
configuration changes.
Note: The most likely scenario in which a Volume Group cannot be converted,
because of insufficient private space, is when a large HP-UX system using
“Extent based Striping” is being used
■ A volume group containing the root volume.
Converting LVM to VxVM
Converting LVM volume groups to VxVM disk groups
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