VERITAS Volume Manager 5.0 Migration Guide (September 2006)

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, etc., 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.