replacing a mirrored disks

[Ray Herbig]

Hello. I have 4 disks 2 mirroring the other two in vg00. I'll call them group A and groupB. One of the disks in group A is failing. My question is if the disk dies what is the best way to remove it. I'm thinking vgreduce vg00 . When I replace it, would a vgcfgbackup / vgcfgrestore -n vg00 vgcfgrestore -n vg00 . Then run vgsync. Sound ok? OR when I add the new disks should I go through the whole remirroring process.

Thanks.

[Patrick Wallek]

If you vgreduce the disks out of the VG then you will have to do a vgextend to put the new disks back in the VG.

I think the best bet would be to put in the new disk, do the vgcfgrestore and then vgsync. The once caveat is if the disk that is failing is set up as a boot disk. If that is the case then you will need to do a mkboot on the new disk to make sure it is bootable if you need it.

[Wieslaw Krajewski]

Hi,

To do vgreduce you must have removed disk free. So you should un-mirror LVs that are on the removed disk (all physical extents on this disk should be unused).
Then you can add new disk and remirror all these logical volumes.volumes.
I think this is the simplest way.
Of course if you can remove mirror copies from the failing disk.

Rgds.

[James R. Ferguson · Accepted solution]

Hi Ray:

# Shutdown your system and replace the disk that is failing.

Boot into single user mode and override the quorum, as:

# ISL> hpux -is -lq /stand/vmunix

# vgcfgrestore -n /dev/vg00 /dev/rdsk/cXtYdZ

# mkboot /dev/rdsk/cXtYdZ

# mkboot -a "hpux -lq /stand/vmunix" /dev/rdsk/CXtYdZ

# lvlnboot -R

# lvlnboot -v #...to verify all is as desired...

# vgchange -a y /dev/vg00

# vgsync /dev/vg00

# shutdown -ry 0

...JRF...

[Ray Herbig]

Here's a crummy graphic. A&B are disk groups and 1 and 2 are the disks in the group. Group B mirrors group A.
A B
[1][2] [1][2]
Disk 1 in both groups is bootable. disk 1 in both groups also contain boot, root and swap.
The disk I want to replace is disk 2 in group A. In order to do that, the data is going to have to be remirrored to group A 1&2.
When I run vgcfgrestore, (after if vgextended vg00) it should restore my vg setup and vgsync should sync the data. I shouldn't have to play around with making disk 1 bootable again should I? I would think the boot area should already be there. OR does vgcfgrestore blow that away?

[MANOJ SRIVASTAVA]

No it doesnt blow up the boot area . What u are trying is correct .

Manoj Srivastava

[Wieslaw Krajewski]

Hi again,

Luckily the failed disk is not bootable one.
So after adding new disk to vg00 (vgextend) remirror only those LVs, that had mirrored copies on the failed disks.

But if you couldn't unmirror LVs because it was impossible to communicate with failed disk, after vgcfgresoring should use command lvsync for every LV that had mirror copies physical extents) on the failed disk.

Rgds.

[James R. Ferguson]

Ray:

I don't believe that you ever indicated which disk as faulty in your original post. The procedure I cited was a general case.

I agree that you should be able to do the 'vgcfgrestore', 'vgchange' & 'vgsync' after you have replaced the faulty disk and not have to exercise the 'mkboot' nor 'lvlnboot' steps.

...JRF...

[Thierry Poels_1]

quote
One of the disks in group A is failing. My question is if the disk dies ....
unquote
If the disk dies ..??? If it's failing, replace it immediateley!!! jeeez. Don't keep on working with disks which make noise like hell, or are starting to fail.
Thierry.

[Ray Herbig]

I like working with failing disks..it gives me meaning. The sound of a head crashing on a platter..music to my ears. Actually the disk started sending out scsi resets yesterday and I lvreduced the mirror to the other working pair. I would like to thank you guys for the imput.