topic Re: vgreduce command in Operating System - HP-UX

vgreduce command

Mark Smith T-Systems — Thu, 24 Jul 2008 14:33:54 GMT

I have an 11.00 N4000 server, the mirrored vg00 root drive is bad and I want to do a vgreduce of the drive before it is removed, and then shutdown and install the replacement drive and reboot:

vgreduce /dev/vg00 /dev/dsk/c0t8d0

Is that good enough, or should I use the "-A"
argument so that a backup is made of the new configuration change? (vgcfbackup executes for the volume group):

vgreduce -A /dev/vg00 /dev/dsk/c0t8d0

Re: vgreduce command

Torsten. — Thu, 24 Jul 2008 14:36:29 GMT

Complete procedures are here:

http://docs.hp.com/en/5991-1236/When_Good_Disks_Go_Bad.pdf

Its not made for 11.00, but most of it applies anyway.

Re: vgreduce command

Vamsidin — Thu, 24 Jul 2008 14:42:46 GMT

Specify the missing disk:

lvreduce -k -m 0 /dev/vg00/lvol1 /dev/dsk/BAD_DISK

otherwise it will try to reduce the PE from the existing mirror.

And

If you have enough free extents on the other disks in the volume group, you have it easy. Simply run # pvmove /dev/hdb
pvmove -- moving physical extents in active volume group "dev"
pvmove -- WARNING: moving of active logical volumes may cause data loss!
pvmove -- do you want to continue? [y/n] y
pvmove -- 249 extents of physical volume "/dev/hdb" successfully moved

**# vgreduce dev /dev/hdb
vgreduce -- doing automatic backup of volume group "dev"
vgreduce -- volume group "dev" successfully reduced by physical volume:
vgreduce -- /dev/hdb

Re: vgreduce command

Fabio Ettore — Thu, 24 Jul 2008 14:52:26 GMT

Hi Mark,

vgreduce without -A I think it's good enough but first you have to un-mirror lvols with command already mentioned:

lvreduce -k -m 0 /dev/vg00/lvol1 /dev/dsk/BAD_DISK

and so on for all lvols.

Then replace the disk and vgextend/pvcreate -B/mirror again by lvextend (starting from 1, 2, 3 and so on). It's important you first mirror lvol1, lvol2 and lvol3 in this order.

HTH.

Best regards,
Fabio

Re: vgreduce command

Mark Smith T-Systems — Thu, 24 Jul 2008 14:53:55 GMT

the whole disk is bad, so I can't do the lvreduce

Re: vgreduce command

Mark Smith T-Systems — Thu, 24 Jul 2008 14:55:27 GMT

Fabio,
yes that seems to make sense to me, plus I will look at that document mentioned above.

Re: vgreduce command

Mark Smith T-Systems — Thu, 24 Jul 2008 14:57:45 GMT

is doing the lvreduce of the mirrors a precaution or necessary do you think?

Re: vgreduce command

Grayh — Thu, 24 Jul 2008 14:57:50 GMT

could you post the o/p

Re: vgreduce command

Torsten. — Thu, 24 Jul 2008 15:01:28 GMT

In this case the lvreduce command will be done with -k and a key like 0 or 1.

Refer to the manual.

Re: vgreduce command

Patrick Wallek — Thu, 24 Jul 2008 15:04:56 GMT

I honestly don't think you need to vgreduce at all. Also, I thought the disks in the N4000 were hot swappable.

What I would do:

1) replace the disk
2) Verify with ioscan that the disk is now accessable (ioscan -fnC disk)
3) Do a vgcfgrestore to restore the VG config to the disk (vgcfgrestore -n vg00 /dev/rdsk/c0t8d0)
4) Activate the VG so the new disk is available (vgchange -a y vg00)
5) Verify the disk is in the VG and shows available (vgdisplay -v vg00)
5) Resync the mirrors. (vgsync vg00)

Re: vgreduce command

Torsten. — Thu, 24 Jul 2008 15:12:02 GMT

I agree with Patrick and would add a third step 5:

5)...
5)...
5) make the disk bootable with mkboot ... (see the manual again). Otherwise you cannot boot from this disk.

;-)

Re: vgreduce command

Mark Smith T-Systems — Thu, 24 Jul 2008 15:15:05 GMT

Hi Patrick,
but this being vg00 it is already "active" and probably can't be made inactive

Re: vgreduce command

Torsten. — Thu, 24 Jul 2008 15:22:07 GMT

You can do the

vgchange -a y vg00

on an activated vg without problems.

Re: vgreduce command

Patrick Wallek — Thu, 24 Jul 2008 15:28:33 GMT

I never said to make the VG inactive.

The 'vgchange -a y vg00' essentially activates the replacement disk within the VG.

Re: vgreduce command

Mark Smith T-Systems — Thu, 24 Jul 2008 15:35:15 GMT

thank you Patrick and Torsten.
I do believe the disks on an N4000 are hot swappable, I will make sure to verify that before I have the tech yank out the bad drive.

Re: vgreduce command

Torsten. — Thu, 24 Jul 2008 15:40:50 GMT

Yes, they are.

Open the "door" on the backside of the n-class and pull the disk.

0/0/2/0.6 is the upper,
0/0/2/1.6 is the lower, but verify this with the label on the chassis.

Re: vgreduce command

Mark Smith T-Systems — Thu, 24 Jul 2008 15:47:50 GMT

the hardware path to my bad disk is 0/0/1/0.8.0

I'll try to find a layout of the chassis for that path just in case it might help the tech, unfortunately I am a remote administrator so I can't be there, they are 300 miles away from me.

Re: vgreduce command

Torsten. — Thu, 24 Jul 2008 15:50:24 GMT

This is for sure not an internal disk.

Can you post an

ioscan -fn

Re: vgreduce command

Torsten. — Thu, 24 Jul 2008 15:51:52 GMT

There must be an external disk chassis connected to the SCSI connector of the core I/O board.

Re: vgreduce command

Mark Smith T-Systems — Thu, 24 Jul 2008 15:55:19 GMT

ioscan hangs because of the bad disk.
do you mind if we take this offline and email?
m-smith@t-systems.com