IBM Support

Unable to run some LVM commands on a split off volume group.

Troubleshooting


Problem

Customers are not able to run some simple LVM commands on a split off volume group using the splitvg command. They receive errors indicating that they cannot run those commands on a snapshot volume group. Examples: When you try to create a logical volume on the snapshot volume group: 0516-1367 mklv: Creation of a new logical volumes is not allowed on a snapshot volume group. 0516-822 mklv: Unable to create logical volume. crfs: 0506-972 Cannot create logical volume for file system. Or when you try to add a new disk to that volume group: 0516-792 extendvg: Unable to extend volume group. 0516-1367 mklv: Creation of a new logical volumes is not allowed on a snapshot volume group. 0516-822 mklv: Unable to create logical volume.

Cause

Such errors are generated because the resulting volume group created from the split off mirror copy is a snapshot volume group that is still in snapshot mode.

Diagnosing The Problem

We should run the command below:


# lsvg data2vg

VOLUME GROUP: data2vg VG IDENTIFIER:
00c732a500004c0000000158073b8f2b
VG STATE: active PP SIZE: 256
megabyte(s)
VG PERMISSION: read/write TOTAL PPs: 15834
(4053504 megabytes)
MAX LVs: 256 FREE PPs: 360 (92160
megabytes)
LVs: 8 USED PPs: 15474
(3961344 megabytes)
OPEN LVs: 7 QUORUM: 1
(Disabled)
TOTAL PVs: 6 VG DESCRIPTORS: 6
STALE PVs: 0 STALE PPs: 0
ACTIVE PVs: 6 AUTO ON: yes
MAX PPs per VG: 65536 MAX PVs: 1024
LTG size (Dynamic): 256 kilobyte(s) AUTO SYNC: no
HOT SPARE: no BB POLICY: relocatable
SNAPSHOT VG: yes PRIMARY VG: 00c732a500004c000000013b2e853dad
MIRROR POOL STRICT: off
PV RESTRICTION: none INFINITE RETRY: no
DISK BLOCK SIZE: 512 CRITICAL VG: no

Based on the output of the command above, the volume group is a snapshot volume group.

This issue will happen on any snapshot volume group that has not been joined back together.

Resolving The Problem

There are two solutions to this issue:

1. Join the volume group again. It will not be a snapshot volume group at this point: consequently, you can run the LVM commands on it. You can use the command below:

# joinvg VGname

2. If you wish to create 2 independent volume groups from the original one, you can rejoin the snapshotvg to the original volume group and then re-splitvg with -i which will allow the volume group to be imported and used as a stand-alone volume group (it will not be a 'snapshot' volume group). Then, any LVM commands will work on the original as well as the new copy of the volume group.

For more information on the splitvg and joinvg commands, please use the links below:

http://www.ibm.com/support/knowledgecenter/en/ssw_aix_71/com.ibm.aix.cmds5/splitvg.htm

http://www.ibm.com/support/knowledgecenter/en/ssw_aix_71/com.ibm.aix.cmds3/joinvg.htm

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Document Information

Modified date:
17 June 2018

UID

isg3T1024560

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