topic Re: vg's on single disk in Operating System - HP-UX

vg's on single disk

BKUMAR — Thu, 11 Dec 2003 22:17:21 GMT

Hi B'Brains,

I Have a 2 volume groups (vg00,vg01) on a server with 18 gb internal disks, hpux 11.0,i get a server on dr-site with 1 72 gb internal disk,how can i plan for both vg's on the same disk...is it possible both vg's on 72 gb disk...pls give ur valuable suggestions/hints

Thx in advance

Re: vg's on single disk

Michael Tully — Thu, 11 Dec 2003 22:20:54 GMT

You can't place two volume groups on the same disk. What I suggest you do is to create the logical volumes from a script (also onto the disk) and have the data for those logical volumes on a backup tape. Even better would be to have the remote system having a second disk if possible.

Re: vg's on single disk

Patrick Wallek — Thu, 11 Dec 2003 22:38:20 GMT

As Michael said, you can NOT have more than 1 VG on a single disk. It just aint gonna happen.

What I would suggest if you can only have the 1 disk on your DR system, is to just create additional LVs in VG00 for you VG01 data from your production machine, mount those LVs as you would on your production system, and restore the data normally.

I don't normally like having non-OS data on VG00, but when you are working in a DR situation sometimes you have to compromise.

Good luck!

Re: vg's on single disk

Helen French — Fri, 12 Dec 2003 00:18:38 GMT

That's one of first rule in LVM that a single disk should be part of one Volume Group only. As Patrick and Michael said, you can have multiple LVs on that 72GB, but it's normally not a good practice to have data volumes (vg01, vg02 etc) on root VG (vg00). If you have another smaller capacity disk free (18 or 36GB), make that as the root VG and you can make use of your 72GB for data.

You may need to consider mirroring your root VGs too. Another thing to remember is your Ignite recovery tape that would be created from the 72GB. If you are going to use that for data storage too, it will be a much bigger archive that will delay your recovery in case of a crash. (You can exclude directories you don't want to be in the recovery tape though).

Re: vg's on single disk

Sunil Sharma_1 — Fri, 12 Dec 2003 01:00:46 GMT

Hi,

There are few rules of LVM and first is

1.One disk can not be part of only one Volume group.
2.One Logical volume can not span across Volume groups.

Sunil

Re: vg's on single disk

Mark Grant — Fri, 12 Dec 2003 01:37:31 GMT

I think you are going to have to go with Patrick's idea if you are only going to be aboe to use the one disk. However, when the logical volumes are created in vg00, /etc/fstab will be wrong. I would suggest just keeping an /etc/fstab.dr for DR purposes which you can use instead.

Maybe someone here will more knowledge about these things could say if it is actually possible to partition the disk and have each partition in a separate volume group. I've never heard of anybody doing that on HPUX and it probably isn't possible but if it is, it could solve your problem.

Re: vg's on single disk

Geoff Wild — Fri, 12 Dec 2003 09:12:54 GMT

As others have said, you can NOT have 2 vg's on 1 disk. You will have to create multiple lvols under a single vg....or buy a second disk....

here's some links for you:

http://docs.hp.com/cgi-bin/otsearch/getfile?id=/hpux/onlinedocs/939/KCParms/KCparam.LVMparmsOverview.html&searchterms=lvm&queryid=20031212-070848

http://docs.hp.com/cgi-bin/fsearch/framedisplay?top=/hpux/onlinedocs/5187-2216/5187-2216_top.html&con=/hpux/onlinedocs/5187-2216/00/00/53-con.html&toc=/hpux/onlinedocs/5187-2216/00/00/53-toc.html&searchterms=Disks%7cUsing%7cthe%7cLogical%7cVolume%7cManager%7cManaging&queryid=20031212-071120

Rgds...Geoff

Re: vg's on single disk

BKUMAR — Fri, 12 Dec 2003 11:09:02 GMT

Thanks all for response

Now My question is vg00 will get restored from ignite image (make_recovery)
I am lucky here that it fits into the single 72 gb data volumes
so i need to increase the vg00 max PE so that i can accomadate the vg01 lv's
As current Max PE per PV is 4350 and i need to increase +2170

i need to know how to proceed here
Thx in advace

Re: vg's on single disk

Patrick Wallek — Fri, 12 Dec 2003 11:14:10 GMT

When you restore with your Ignite tape, Ignite should automagically increase the max PE per PV since you are installing onto a larger disk.

One thing you may have a problem with on a disk that large though the PE Size. It may be too small.

Your best bet would be to install from the Ignite tape interactively and verify and change the VG parameters as appropriate.

You could even go ahead and have it create your extra LVs at this point as well.

Good luck.