VERITAS Volume Manager 3.5 Migration Guide (September 2004)

Chapter 2

Converting LVM to VxVM

Restoring the LVM Volume Group Conﬁguration

NOTE vgrestore (1M) should not be confused with the LVM command, vgcfgrestore (1M).

vgcfgrestore is used to restore the LVM conﬁguration information saved by vgcfgbackup

(1M), but it will not restore your device ﬁles and /etc/fstab entries. It also will not import

and activate the volume group, nor will it clean up any VxVM information left around.

However, vgrestore will do all of this for you.

Rollback to LVM Using vxvmconvert

Rollback replaces the VxVM disk groups with the original LVM volume groups. During conversion,

vxvmconvert saves a “snapshot” of the original LVM metadata and associated conﬁguration ﬁles, such as

/etc/fstab and LVM device ﬁles. It restores only the LVM metadata and conﬁguration ﬁles from this

snapshot; user data is not changed. This method can only be used if no changes have been made to the

conﬁguration since the conversion.

For example, if a disk has been added to the disk group or if the names of any logical volumes have changed,

you cannot use the rollback method.

NOTE In many cases, if you choose the rollback method and the conﬁguration has changed, you

receive an error and must use the full restore method.

If you used the workaround of creating symbolic links from the old LVM names to the new

VxVM names described in step “5. Planning for new VxVM logical volume names” on page 15,

you must remove the symbolic links you created before beginning the rollback.

This “snapshot” is kept on the root ﬁle system. The presence of this snapshot should not be

taken as assurance that full off-line backups will not be needed. See “4. Backing up your LVM

conﬁguration and user data” on page 14 for speciﬁc information on backups.

To rollback to LVM from the VxVM conversion, run vxvmconvert and choose option 3. See “Examples” on

page 22 for illustration.

CAUTION Do not use this option unless you are certain that you want to restore LVM volume groups.

Once this is run, the VxVM disks that were created as a result of the original conversion from

LVM to VxVM no longer exists. This option is not a full complement to vxvmconvert. It simply

writes the saved LVM metadata back on top of the disks. Those data can only be considered

valid for the period of time when the logical volumes are off-line. If the VxVM conﬁguration has

been brought online, the metadata in the rollback snapshot should be considered obsolete. See

“Full LVM Restoration” on page 20 for speciﬁc information.

Full LVM Restoration

If you need to restore the original LVM conﬁguration, but changes have been made to the VxVM

conﬁguration, you cannot use the rollback option of vxvmconvert. In this case, you must restore the user data

in addition to restoring the old LVM metadata and associated conﬁguration ﬁles. You may need to use this

method if the disks in use by the LVM/VxVM volumes were corrupted during or after conversion.

NOTE The snapshot of LVM internal data is kept on the root ﬁlesystem.