topic Re: Recreate Volume Group in Operating System - HP-UX

Recreate Volume Group

Neil Wilson_2 — Thu, 16 Aug 2001 12:16:44 GMT

The Physical Extents are too small for a VG. I need to recreate the VG with a larger PE size. All LVs are mirrored. What is the best way to do this? recreate a new VG, LVs and copy from existing or use lvsplit? how do i do this?

Re: Recreate Volume Group

harry d brown jr — Thu, 16 Aug 2001 12:24:16 GMT

I believe that if you split mirror's, they still belong to the VG (its been a year since I've played with mirrors), and since the PE is a definition of the VG, you have to delete the VG and recreate it with large PE's. So, I'd backup the LV's (twice), delete the LV's, then the VG, and then do my restores.

Re: Recreate Volume Group

James R. Ferguson — Thu, 16 Aug 2001 12:34:58 GMT

Hi Neil:

I presume that you are not dealing with vg00. If that is the case, I would look to using Ignite 'make_tape_recovery' to reinstall and due your resizing changes via the advanced filesystem options menus.

Thus, I presume that the volume group isn't vg00. Then, since you are going to have to bite-the-bullet and recreate the volume group to change the LVM geometry, 'lvsplit' isn't going to gain you much. The bit map created by a split remains in existence only until a merge is completed, or until one of the logical volumes is extended, reduced, split again, or until the system is rebooted.

I think you will want to 'lvreduce' and 'vgreduce' the volume to gain the physical disk you will use to recreate the volume group. Then make a new volume group with a new volume group number. Create your logical volumes, and a set of mount points. Then using 'cpio' copy your filesystems from their current mount point to the new ones:

# cd /old_mount_point
# find . | cpio -pudlmv /new_mount_point

When done, edit /etc/fstab replacing the "old_mount_point" with the "new_mount_point" and remove the "old" ones.

Lastly, remirror your newly created logical volumes on your newly created volume group.

Regards!

...JRF...

Re: Recreate Volume Group

AlHassani Mohamed — Fri, 17 Aug 2001 07:02:27 GMT

Hi
yo can use the pvmove to copy a logical Volume
from a disk to other if this are persisting.
look man page for pvmove.

regards
mo.

Re: Recreate Volume Group

Sundar_7 — Fri, 17 Aug 2001 08:31:12 GMT

Hey Neil,

I was wondering why U fancy destorying the entire VG and then recreating it ..

U can always extend it...is it not ?

Add a new disk..

# pvcreate

# vgextend

This should be an easy and safe way in extending the number of PE's

See if this helps and assing the points :-)

Sundar

Re: Recreate Volume Group

Andrew R. — Sun, 19 Aug 2001 18:40:03 GMT

I do agree with JRF as this is the only way, you have to recreate the VG. I am having the same problem where my existing VG has 4GB disks and now I need to add 8GB disks to the VG of course I couldn't because the max extents 1075 with the default extent size 4MB So I recreated the VG with

#vgcreate -p 255 -s 32 /dev/vgxx /dev/dsk/c.t.d

This consumes some more over head but it is safe.
Good Luck