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

17Converting LVM to VxVM
Converting LVM volume groups to VxVM disk groups
Initializing disks for VxVM use
To initialize the disk for VxVM use, use the vxdiskadm command, selecting the
option:
1) Add or initialize one or more disks
Or use the command:
# vxdisk init disk_name
VxVM utilities will not tamper with disks that are recognized as owned by LVM
(by virtue of the LVM disk headers). If you attempt to use
vxdisk init, or vxdiskadm on an LVM disk without using the pvremove
command first, the command will fail.
Converting LVM volume groups to VxVM disk groups
This section outlines the process for converting LVM volume groups to VxVM
disk groups.
Note: It is recommended that you read through this section carefully before
beginning any volume group conversion.
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.