VERITAS Volume Manager 3.1 Migration Guide

Converting LVM to VxVM
Converting LVM Volume Groups to VxVM Disk Groups
Chapter 226
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.