topic Re: Problem while extending the VG in Operating System - HP-UX

Problem while extending the VG

Mahesh Babbar — Wed, 20 Oct 2004 09:54:52 GMT

Hi Gurus,

I have HPUX clusters connected to XP512.

I have one VG which already in place. and I want to extend it.

While extending it gives following problem:

# vgextend /dev/cad /dev/dsk/c4t15d5
vgextend: Warning: Max_PE_per_PV for the volume group (3473) too small for this PV (8690).
Using only 3473 PEs from this physical volume.
Volume group "/dev/cad" has been successfully extended.
Volume Group configuration for /dev/cad has been saved in /etc/lvmconf/cad.conf

The size of the LUN is 34 GB (OPEN-L).

The details of VG is:
--- Volume groups ---
VG Name /dev/cad
VG Write Access read/write
VG Status available, exclusive
Max LV 255
Cur LV 1
Open LV 1
Max PV 16
Cur PV 8
Act PV 8
Max PE per PV 3473
VGDA 16
PE Size (Mbytes) 4
Total PE 27776
Alloc PE 25600
Free PE 2176
Total PVG 0
Total Spare PVs 0
Total Spare PVs in use 0

TIA

Mahesh

Re: Problem while extending the VG

Sanjay_6 — Wed, 20 Oct 2004 09:59:13 GMT

Hi Mahesh,

you are running into the MX_PE per PV limit for the VG. This is a standard problem for unix admin in recent days.

A Look at this doc from itrc would be helpful in understanding the situation,

http://www2.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000063201757

The itrc doc id is KBRC00004285

Hope this helps.

Regds

Re: Problem while extending the VG

Sundar_7 — Wed, 20 Oct 2004 10:01:05 GMT

Mahesh,

It looks like the PVs that are already part of the volume group are of size 13.X GB. When the VG is created, MAX PE per PV is set to the biggest PV size added to the VG at the time of creation.

Now you could only use 4 * 3473 MB of 34 GB LUN you just added.

Are you running 11i or 11.0.

If 11i, I have an unsupported program that can help you increase the PE size or Max PE per PV without recreating the Volume group.

Only other option is to recreate the volume group with a bigger Max PE per PV value.

- Sundar.

Re: Problem while extending the VG

Pete Randall — Wed, 20 Oct 2004 10:01:10 GMT

The PE Size and Max PE per PV default to fit the size of the original disk in the VG. The only way to change this is to re-create the VG from scratch. Back up the data, remove the VG, create the VG, specifying suitable PE Size and Max PE per PV figures, and restore the data.

Pete

Re: Problem while extending the VG

Geoff Wild — Wed, 20 Oct 2004 10:01:40 GMT

You will have to recreate the voulme group...

For a 34GB LUN, you need to create a vg like so:

vgcreate -s 8 -p 128 /dev/vgXX /dev/dsk/cXtXdX

man vgcreate for more info

Rgds...Geoff

Re: Problem while extending the VG

Cheryl Griffin — Wed, 20 Oct 2004 10:02:25 GMT

The volume group was created with too low of a max_pe setting to allow for a larger disk.

There is an enhancement request to allow this setting to be changed on-the-fly, but that has not been addressed yet.

You will have to recreate the volume group to accommodate the larger disks. Be sure to specify -e max_pe to allow for future growth beyond these disks.

Re: Problem while extending the VG

Mahesh Babbar — Wed, 20 Oct 2004 10:22:23 GMT

Thanks to all for replying so fast.

Sundar : Can you please elaborate on the utility which can do the trick w/o recreating the VG.

Best Regards
Mahesh

Re: Problem while extending the VG

Sundar_7 — Wed, 20 Oct 2004 11:36:35 GMT

Mahesh,

Attached is the tool I was talking about. There are lot of pre-requisites that have to be met for the tool to succeed.

I would strongly recommend taking the complete backup of VG before using the tool.

also remember this tool is not supported by HP.

- Sundar.