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

12 VxVM and LVM

Coexistence of VxVM and LVM disks

Both LVM disks and VxVM disks can exist together on a system. The LVM disks

are detected and displayed as such by VxVM. LVM disks are not selected by

VxVM for initialization, addition, or replacement.

Mirrors Mirrors (plexes)

Both LVM and VxVM support mirrors. Mirrors can be used to store multiple copies of a

volume’s data on separate disks.

In LVM, you can create mirrors using the MirrorDisk/UX product. Mirrors allow duplicate

copies of the extents to be kept on separate physical volumes. MirrorDisk/UX supports

up to 3 copies of the data.

A VxVM mirror consists of plexes. Each plex is a copy of the volume. A plex consists of

one or more subdisks located on one or more disks. VxVM volumes can have up to 32

mirrors (where each plex is a copy of data). Mirroring features are available with an

additional license.

Export Deport

In LVM, exporting removes volume group information from /etc/lvmtab. The volume

group must have already been deactivated.

Similarly in VxVM, deport makes a disk group inaccessible by the system.

Import Import

In LVM, import adds a volume group to the system and the volume group information to /

etc/lvmtab but does not make the volumes accessible. The volume group must be

activated by the vgchange -a y command in order to make volumes accessible.

In VxVM, import imports a disk group and makes the diskgroup accessible by the system.

Bad block pool No similar term

In LVM, the bad block pool provides for the transparent detection of bad disk sectors, and

the relocation of data from bad to good disk sectors.

The bad block reallocation feature does not exist in VxVM because the vectoring of bad

blocks is now done by most hardware.

/etc/lvmtab No similar term

The /etc/lvmtab file contains information about volume groups that are accessible by

a system.

Table 1-1 A conceptual comparison of LVM and VxVM

LVM term VxVM term