volume group size in a cluster environment

[khilari]

Hi people, well i wanted to know the impliactions of increasing volume group size in a cluster environment. As to lets say you have to increase the size of a volume group on a running cluster... Do, u have to unmount it first or can u do it online !!!
Thanks

[Shahul]

Hi,

You can not extend a volume group when it is activated in shared mode. to my knowledge, in a cluster VG is activated in shared mode. So you can not extend online when it's running in a cluster.

Regards
Shahul

[A. Clay Stephenson]

Your question has no meaning. Volume groups are not mounted; filesystems are mounted. If your question is "Can I increase the size of a logical volume and then the size of the corresponding filesystem while the cluster is active?" then the answer is yes. In fact, you can do this with the package using the filesystem active and there is nothing else to do on any of the other hosts because this LVM metadata are carried in the reserved areas of the LVM disks themselves. If the VG is activated on another host, the new LVOL size will be visible with no additional work.

Things get more complicated if you want to change a VG size by adding additional PV's.

[Stephen Doud]

To increase the capacity of a volume group use vgextend while the VG is active.
VGextend does not work when the VG is activated in "shared" mode, but it can be done when the VG is activated in normal or "exclusive" modes.

A walk-through is given in document ID: UXSGLVKBAN00000002
TITLE: Adding A Disk To A Volume Group In A ServiceGuard Package

A disk/LUN can be added to a VG while the package that controls the VG is running.

[Geoff Wild]

You don't need to un mount file systems to increase them nor add disks to existing volume groups.

You will have to vgexport that vg on other nodes that have access to it anr re-vgimport it. If you change a file system mount point (or add one), you have to make sure you update your control script and copy it to the other node(s).

Rgds...Geoff

[Siju Vadakkan]

before u start disable the package switching with cmmodpkg -d on the node where the package is running . This will avoid the inconsistency of vg in case the package fails inbetween.




extend the vg on the node where it is activated and and then export it.

1. vgextend
2. vgexport -v -p -s -m

3. ftp the mapfile to second node.

On the second node
====================
1.vgexport (to remove the vg)
2.mkdir /dev/
3.mknod /dev//group c 64 (minor number should be the same.

4.vgimport -v -s -m