topic Re: Max_PE_per_PV for vg00 in Operating System - HP-UX

Max_PE_per_PV for vg00

Rob Saunders — Thu, 11 Apr 2002 11:52:26 GMT

Is it possible to increase the "Max_PE_per_PV" for vg00 ?

I'm trying to extend vg00 onto another disk but when I do so I get the message:

vgextend: Warning: Max_PE_per_PV for the volume group (2500) too small for this PV (8683).

Using only 2500 PEs from this physical volume.

Volume group "vg00" has been successfully extended.

Volume Group configuration for /dev/vg00 has been saved in /etc/lvmconf/vg00.conf

Obviously, I'd like to use all of this disk, not just a part of it. I can't delete and recreate the vg00 volume group (without a complete rebuild) as this contains the OS.

Re: Max_PE_per_PV for vg00

Clemens van Everdingen — Thu, 11 Apr 2002 11:56:46 GMT

Hi,

This is only changeable at creation time of the VG.
So you need to recreate the vg00.
Maybe ignite is here a solution.

C.

Re: Max_PE_per_PV for vg00

Jeff Schussele — Thu, 11 Apr 2002 12:01:39 GMT

Rob,

Sorry, nope.
Set at creation & unchangeable.
Best option would be to recreate with Ignite.

Rgds,
Jeff

Re: Max_PE_per_PV for vg00

Bill Hassell — Thu, 11 Apr 2002 12:03:02 GMT

Sorry, the Max_PE_per_PV is setup when the volume was created. It's very common to not plan ahead for large increases in a volume group and thus the maxPE value won't be large enough. The volume must be removed and recreated. Since this is vg00, your only choice is Ignote/UX. Download the latest version (always) from:

http://www.software.hp.com/products/IUX/

and once installed (no reboot needed), use the commmand:

make_tape_recovery -AIv -a /dev/rmt/WhatEver

When completed, you can reinstall using this tape and specify during filesystem setup that vg00 has additional disk(s) and the maxPE value will be adjusted prior to creating vg00.

However, there is a bigger question: why is vg00 being increased? For normal (easy to manage) installations, vg00 is just the operating system and applications, no data. It is very common that poor install techniques by some applications will create unauthoriZed directories in / and fill the / lvol. Rather than try to work around this problem, it is better to put these rogue applications and datafiles in the 'right' location, typically /opt/RougeApplicationName or similar.

vg00 is unique in that it contains the opsystem and is part of a bootable disk. Other data should not be stored in vg00 other than config files and application binaries.

Re: Max_PE_per_PV for vg00

Juan Manuel López — Thu, 11 Apr 2002 12:10:37 GMT

Hi,
You have to increase the vg00 with a new disk with the same caracteristics that old disk.
good luck !

Juanma.

Re: Max_PE_per_PV for vg00

Rob Saunders — Thu, 11 Apr 2002 12:28:30 GMT

Thanks all, The answer's pretty much as expected (unfortunately!)

[FYI. The reason for wanting to extend vg00 is for future Ignite's of systems which ordinarily are created on multple VGs. For these systems, it is not necessary to recreate the multiple VG, so we can potentially Ignite them by putting everything (not that much) into vg00]

Re: Max_PE_per_PV for vg00

Rob Saunders — Thu, 11 Apr 2002 14:04:25 GMT

Okay, I've tried again to extend the VG, but Ignite doesn't like this.

The system I've got is an A500 with 2 internal disks (9G + 36G). Does the fact that the disk sizes are different prevent the max_pe_per_pv from being changed. (I would have thought that max_pe_per_pv should only be an upper limit, rather than a hard value)

(I've now given up on the idea and resorted to multiple VGs which I won't be able to Ignite, your further comments are welcome however and I may try again at a later date)

Re: Max_PE_per_PV for vg00

James R. Ferguson — Thu, 11 Apr 2002 14:12:38 GMT

Hi Rob:

If you have multiple disks that you are going to use to form a volume group, and the disks are of different sizes, and you do not explicitly specify 'max_pe', for instance, then the value will be chosen will be that of the *first* disk seen by 'vgcreate'.

Once set, there is no way to alter 'max_pe'. Your only recourse is to destroy and recreate the volume group.

Ignite is the preferred way to circumvent your problem by rebuilding your system. Choose the "advanced installation" tab for more LVM options. You will be able to select your root disk. Choose the 36GB disk and establish it as vg00. This size disk should be more than adequate for your needs. In my opinion, avoid multiple physical volumes for vg00 at all costs.

Regards!

...JRF...