topic Re: vgreduce in Operating System - HP-UX

vgreduce

SYS_MONEXT — Tue, 16 Sep 2003 06:45:58 GMT

I want to inverse alternate link.
root@jazz:/root> vgdisplay -v stk07
--- Volume groups ---
VG Name /dev/stk07
VG Write Access read/write
VG Status available
Max LV 255
Cur LV 1
Open LV 1
Max PV 16
Cur PV 1
Act PV 1
Max PE per PV 8468
VGDA 2
PE Size (Mbytes) 4
Total PE 8466
Alloc PE 8466
Free PE 0
Total PVG 0

--- Logical volumes ---
LV Name /dev/stk07/lvol1
LV Status available/syncd
LV Size (Mbytes) 33864
Current LE 8466
Allocated PE 8466
Used PV 1

--- Physical volumes ---
PV Name /dev/dsk/c4t0d7
PV Name /dev/dsk/c5t1d7 Alternate Link
PV Status available
Total PE 8466
Free PE 0

The commands are :
#vgreduce stk07 /dev/dsk/c4t0d7
#vgextend stk07 /dev/dsk/c4t0d7

But : Can I do it online without any danger for the data. This machine is very "fragil" (production)

Thank yo in advance.

Arnaud

Re: vgreduce

Mark Grant — Tue, 16 Sep 2003 06:48:50 GMT

No problem.

The commands you have commented out there will do the trick and you can certainly do it online with no danger.

Re: vgreduce

SYS_MONEXT — Tue, 16 Sep 2003 07:04:21 GMT

Thank you.

This way works fine as you said it.

Arnaud

Re: vgreduce

Todd McDaniel_1 — Tue, 16 Sep 2003 18:30:50 GMT

Im curious what your reasoning is for doing this. If it is just a matter of changing the primary disk okay, thats fine.

If you are doing it to try to take advantage of alternating disks for multipathing i/o issues... You wont get a desired result, to some degree however you will...

By alternating back and forth on the alternate links, you gain some i/o benefit by the fact that you have moved half your data flow(potentionally) to the other controller when you have dual pathing. however, as you may know, which ever path is considered the alt path for each disk will not be used if/until the current primary path dies... the alt path will not be used at all until that happens...unless you have some application that forces data down both paths(ie Powerpath/Securepath) for emc and compaq...

Just a few thoughts for your enjoyment.

Re: vgreduce

aparna challagulla — Mon, 29 Sep 2003 00:23:15 GMT

hi Arnaud,

yes u can do this online without any problems. we too have run these commands on our production without any difficulty.

aparna

Re: vgreduce

Steven E. Protter — Mon, 29 Sep 2003 00:27:55 GMT

Prior to touching this system:

#!/usr/bin/sh
/opt/ignite/bin/make_tape_recovery -Av -x inc_entire=vg00

Take a good backup that will let you reocver vg00.

Also might want to include the vg in question depending on the data. If its got hot databases, they need to be down or backed up using proper database backup tools.

The commands look safe, but I don't mess with a production system without at least two modes to back out the change.

Also, if there is a test system available, test the commands out there.

Its production. You can't be too anal about it.

SEP

Re: vgreduce

Thierry Poels_1 — Mon, 29 Sep 2003 01:07:30 GMT

Hi,

to exchange primary and alternate link, just use "pvchange -s xxxx".

best regards,
Thierry.