HP-UX 11i v3 Using LVM Logical Volume Snapshots (September 2010)
Using LVM logical volume snapshots
Technical white paper
Table of contents
Using LVM logical volume snapshots ...................................................................................................... 1
Abstract .............................................................................................................................................. 2
Audience ............................................................................................................................................ 2
HP-UX LVM snapshot overview .............................................................................................................. 2
Types of snapshot logical volumes ...................................................................................................... 2
Snapshot uses .................................................................................................................................. 3
Difference between snapshot logical volumes and split logical volumes .................................................. 3
Snapshot tree .................................................................................................................................. 4
Data unsharing on snapshot logical volumes ....................................................................................... 4
Creating and administering snapshots .................................................................................................... 7
Creating snapshots ........................................................................................................................... 8
Extending the pre-allocated extent pool ............................................................................................. 10
Enabling the automatic increase of pre-allocated extents ..................................................................... 12
Changing the Attributes of a Snapshot Logical Volume ....................................................................... 14
Changing the attributes of a logical volume having snapshots ............................................................. 16
Deleting logical volumes on a snapshot tree ...................................................................................... 16
Displaying Snapshot Information ...................................................................................................... 18
Importing volume groups with snapshots ........................................................................................... 26
Reconfiguring a volume group using vgmodify................................................................................... 27
Migration of volume group version using vgversion ............................................................................ 27
pvmove , vgmove, and lvmove commands ........................................................................................ 28
vgreduce command ........................................................................................................................ 28
lvsplit and lvmerge commands ......................................................................................................... 28
vgchange command ....................................................................................................................... 28
Configurable location for the volume group configuration file .............................................................. 29
Limitations when using snapshots ......................................................................................................... 29
Common use examples....................................................................................................................... 30
Recommended practices ..................................................................................................................... 32
Error messages .................................................................................................................................. 32
Performance numbers ......................................................................................................................... 35
Read performance.......................................................................................................................... 35
Write performance ......................................................................................................................... 36
Configuration file size ........................................................................................................................ 38
For more information .......................................................................................................................... 39
Feedback .......................................................................................................................................... 39