HP-UX System Administrator's Guide: Logical Volume Management (762803-001, March 2014)

To back up a mirrored logical volume containing a file system, using lvsplit and lvmerge,

follow these steps:

1. Split the logical volume /dev/vg00/lvol1 into two separate logical volumes as follows:

# lvsplit /dev/vg00/lvol1

This creates the new logical volume /dev/vg00/lvol1b. The original logical volume /dev/

vg00/lvol1 remains online.

2. Perform a file system consistency check on the logical volume to be backed up as follows:

# fsck /dev/vg00/lvol1b

3. Mount the file system as follows:

# mkdir /backup_dir

# mount /dev/vg00/lvol1b /backup_dir

4. Perform the backup using the utility of your choice.

5. Unmount the file system as follows:

# umount /backup_dir

6. Merge the split logical volume back with the original logical volume as follows:

# lvmerge /dev/vg00/lvol1b /dev/vg00/lvol1

NOTE: lvsplit is not supported on snapshot logical volumes. lvmerge is not supported for

snapshots as well as logical volumes having snapshots.

3.3.21 Backing Up and Restoring Volume Group Configuration

It is important that volume group configuration information be saved whenever you make any

change to the configuration such as:

• Adding or removing disks to a volume group

• Changing the disks in a root volume group

• Creating or removing logical volumes

• Extending or reducing logical volumes

Unlike fixed disk partitions or nonpartitioned disks that begin and end at known locations on a

given disk, each volume group configuration is unique, changes, and uses space on several disks.

If you back up your volume group configuration, you can restore a corrupted or lost LVM

configuration in the event of a disk failure or corruption of your LVM configuration information.

The vgcfgbackup command creates or updates a backup file containing the volume group

configuration; it does not back up the data within your logical volumes. To simplify the backup

process, vgcfgbackup is invoked automatically whenever you make a configuration change as

a result of using any of the following commands:

lvmergelvlnbootlvextendlvcreatelvchange

vgcreatelvsplitlvrmbootlvremovelvreduce

vgmodifyvgextendvgchange

pvmovepvchange

vgreduce

For volume group Version 2.2 and higher, the vgchange command automatically takes a backup of the volume group

configuration during deactivation if it has associated snapshots, provided the VG is activated neither in read-only mode

nor with -l option. This behavior was different in releases prior to 11i v3 March 2014 update, where the automatic

backup was done for volume group version 2.2 irrespective of the presence or absence of snapshots. In all earlier volume

group versions, there is no automatic backup when the vgchange command is used.

72 Administering LVM