topic Re: Recovering Lost Volume Group Definition in Operating System - HP-UX

Recovering Lost Volume Group Definition

Vivek Shrivastava_1 — Thu, 20 May 2004 11:49:17 GMT

Hi,

Because of a bad disk one of my volume group is not working.

I need to ecover some how the Definition of each logical volume (like size, name...)

Please help me ASAP, i would really appreciate your help.

thanks

Re: Recovering Lost Volume Group Definition

A. Clay Stephenson — Thu, 20 May 2004 11:55:02 GMT

vgcfgrestore -n /dev/vg01 /dev/rdsk/c1t6d0

You supply the correct VG and device node. That will write the VG data to the new disk.
You can then do a vgchange -a y /dev/vg01 to activate the volume. The lvol names should still be in /dev/vg01/.

Now, learn to use MirrorUX so that this is a non-event.

Re: Recovering Lost Volume Group Definition

Steven E. Protter — Thu, 20 May 2004 12:08:37 GMT

Side note: Mirror/ux is a wonderful product, but you do have to pay for the license one per processor.

A codeword from http://licensing.hp.com is required to use the product.

SEP

Re: Recovering Lost Volume Group Definition

Vivek Shrivastava_1 — Thu, 20 May 2004 13:03:25 GMT

Thanks for such quick reply.

I don't have any extra disk at this point. Would it be possible to create file which ahs the definition of each logical volume for the bad volume group?

Just to add more information, there are two disks in this volume group and only one of them is bed.

What would be the procedure to recover after the bad disk is replaced.

Please answer for both of the question. i have to show the logical volume definition list before they replaced the bad disk.

Waiting for help.

VivekS

Re: Recovering Lost Volume Group Definition

Mel Burslan — Thu, 20 May 2004 13:10:42 GMT

the only information you can get which logical volume is configured at what size is by doing a vgdisplay -vg vg01 (assuming vg01 has the bad disk, if not change it to yours). It will complain many times that it could not query all disks attached to this group but ignore that. You already know that one disk is bad.

After they replace the disk, you need to run the command

vgcfgrestore -n vg01 /dev/rdsk/c#t#d#

this will restore the logical volume structure on the new disk but not the filesystems themselves. You will need to check all the filesystems on this volume group and re-create them by

newfs -F vxfs /dev/vg01/lvolXXX

then hope that you have a pretty recent good backup that you can restore them from.

Re: Recovering Lost Volume Group Definition

Sanjay_6 — Thu, 20 May 2004 13:21:26 GMT

Hi,

Replace the disk and do a vgcfgrestore. This will recreate the info back on the disk. Make sure you are using a disk of capicity that is equal to or more than the previous disk.

Do "man vgcfgrestore" for more help on the commands.

If the disk is mirrored, use vgsync to resync the mirror.

Try this link from itrc for more instructions.

http://www1.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000066374050

The itrc doc id is KBAN00000347.

Hope this helps.

Regds

Re: Recovering Lost Volume Group Definition

Vivek Shrivastava_1 — Thu, 20 May 2004 15:31:38 GMT

Thanks Sanjay,

For such a good link. You solved my half of the problem. I still need to produce some output which can just provide following two information for each logical volume in bad logical voule.

1. Name of the LV
2. Size of the LV in MB

really looking for some help.

thanks

Re: Recovering Lost Volume Group Definition

Sanjay_6 — Thu, 20 May 2004 15:40:16 GMT

Hi,

Unless the vg is active you cannot get this info.

If the vg is active, you can get this info using vgdisplay / lvdisplay.

vgdisplay -v /dev/vg_name will give the detail info on the vg and the lv names and their sizes including the disks configured into the vg.

lvdisplay gives more detailed info about a specific lv.

If the vg is not active, you cannot get this info.

Hope this helps.

Regds

Re: Recovering Lost Volume Group Definition

Vivek Shrivastava_1 — Thu, 20 May 2004 17:42:37 GMT

thanks for reply!

So basically we can't get the info from the vgxx.conf file. There are lots of files in /etc/lvmconf directory. I figured out the name by looking into /dev/vgxx directory still looking for size.

vgcfgrestore must be reading this info from somewhere.

can't we create mapfile from the inactive volume group?

Please someone come with some great idea.

waiting fro help.

thanks

Re: Recovering Lost Volume Group Definition

Mel Burslan — Thu, 20 May 2004 17:53:21 GMT

I do not think that there is any utility to read the vgXX.conf file out there as it is a binary file.

Did you try activating the volume group ?

vgchange -a y /dev/vg01

Re: Recovering Lost Volume Group Definition

Patrick Wallek — Thu, 20 May 2004 21:11:11 GMT

You do not need to know any of the LV information to replace the disk. When you replace the disk you just need to do a 'vgcfgrestore -n vgname /dev/dsk/c?t?d?' Then you need to do a 'vgchange -a y vgname' to reactivate the volume group. Once you do that your VG is back to its previous state just without any of the data. After the vgchange you can do a 'vgdisplay -v vgname' to get all of the information for that volume group.

I'm not sure I understand exactly why you need the information right now.

Re: Recovering Lost Volume Group Definition

Naveej.K.A — Thu, 20 May 2004 22:04:13 GMT

hi,

there is still another way to find out the name of the logical volumes (if raw logical volumes are not used) from the /etc/fstab, where you will get the vgname as well as the logical volume name.

with best wishes
naveej

Re: Recovering Lost Volume Group Definition

zx_yu — Thu, 20 May 2004 22:49:48 GMT

try this:
#vgchange -q n -a y /dev/vg01
#vgdisplay -v /dev/vg01
if the volume group can be activating by -q n,then you can find the information of logical volume

Re: Recovering Lost Volume Group Definition

Shaikh Imran — Thu, 20 May 2004 23:36:23 GMT

Hi,
For getting the name of the LV try your
/etc/fstab.
========================================
What has happened is the past
Tip for future:
Please keep the hard & soft copies of the following parameters.
bdf
/etc/fstab
/etc/passwd
/etc/hosts
/etc/group
vgdisplay ( of all VG's )
lvdisplay of all LV's
Please donot foget to do vgcfgbackup always or put it in the cron.
kernel parameters

You can make a script to do all the above activities and redirect it to a file and keep it for future reference.

Regards,
Imran

Re: Recovering Lost Volume Group Definition

Isralyn Manalac_1 — Thu, 20 May 2004 23:55:07 GMT

Over and above what the guys have told you, what I regularly do is to capture the system configuration information through System Information Reporter (SIR). It is a good practice to do so, so you'll have something to refer to in case a disaster strikes.

Regards,
Ira

Re: Recovering Lost Volume Group Definition

James Lynch — Fri, 21 May 2004 08:18:03 GMT

You can use the "-l" option to vgcfgrestore to get a listing of the VG config. vgcfgrestore reads this information from the /etc/lvmconf/vgXX.conf file.

JL

Re: Recovering Lost Volume Group Definition

Vivek Shrivastava_1 — Fri, 21 May 2004 08:24:52 GMT

Thanks Guys,

I guess i will simply restore it.

Manalac,

Could please provide some information on "System Information Reporter (SIR)." ? like how do i run it?

thanks