topic Re: Changing Alterante Paths. in Operating System - HP-UX

Changing Alterante Paths.

Amit Manna_6 — Thu, 15 Dec 2005 04:31:18 GMT

Hi,
I have the following PV configuration.

pvdisplay -v /dev/dsk/c4t4d1 | pg
Device file path "/dev/dsk/c4t4d1" is an alternate path
to the Physical Volume. Using Primary Link "/dev/dsk/c6t4d1".
--- Physical volumes ---
PV Name /dev/dsk/c6t4d1
PV Name /dev/dsk/c4t4d1 Alternate Link
PV Name /dev/dsk/c15t4d1 Alternate Link
PV Name /dev/dsk/c16t4d1 Alternate Link

The correct one should be

PV Name 33 B /dev/dsk/c4t4d1
PV Name /dev/dsk/c15t4d1 Alternate Link

Can anybody help me out how to change this

Re: Changing Alterante Paths.

Slawomir Gora — Thu, 15 Dec 2005 04:43:44 GMT

Hi,

you need to:
vgreduce /dev/your_vg_name /dev/dsk/c6t4d1
vgextend /dev/your_vg_name /dev/dsk/c6t4d1

then you will have such order:
/dev/dsk/c4t4d1
/dev/dsk/c15t4d1
/dev/dsk/c16t4d1
/dev/dsk/c6t4d1

Re: Changing Alterante Paths.

Devender Khatana — Thu, 15 Dec 2005 04:46:49 GMT

Hi,

The best way to do this is to set it while creating VG.

If you remove the VG from the three alternate links than obviously the forth one will remina as primary. At this stage you can extend it back to the same PVs.

#vgreduce /dev/vgname /dev/dsk/c6t4d1

#vgreduce /dev/vgname /dev/dsk/c15t4d1

#vgreduce /dev/vgname /dev/dsk/c16t4d1

If after first command itself it does prompt for the correct device to be primary then you need not to reduce it from other two. Can simply reextend it to the same disk.

#vgextend /dev/vgname /dev/dsk/c6t4d1

Repeat for others if required.

Good Luck.
Devender

Re: Changing Alterante Paths.

RAC_1 — Thu, 15 Dec 2005 04:55:47 GMT

You can do that with pvchange also.
pvchange -s

Re: Changing Alterante Paths.

Devender Khatana — Thu, 15 Dec 2005 04:59:11 GMT

Yes I agree. The simplest way of activating it will be

#pvchange -s /dev/dsk/c4t4d1

HTH,
Devender

Re: Changing Alterante Paths.

Muthukumar_5 — Thu, 15 Dec 2005 05:41:46 GMT

see pvchange man page on EXAMPLEs part. It is having an example to suit your requirement. Answer is using pvchange -s will change controller path.

-Muthu

Re: Changing Alterante Paths.

Arunvijai_4 — Thu, 15 Dec 2005 05:44:23 GMT

http://docs.hp.com/en/B2355-60105/pvchange.1M.html

Re: Changing Alterante Paths.

Amit Manna_6 — Thu, 15 Dec 2005 08:04:24 GMT

If we use pvchange that will not sustain after reboot. Any alternatives please

Re: Changing Alterante Paths.

James R. Ferguson — Thu, 15 Dec 2005 08:15:20 GMT

Hi Armit:

You are correct, using 'pvchange' will not retain you new pvlink order following a reboot.

The "correct" way is to 'vgreduce' and 'vgextend' so that you achieve the order of alternate paths you want.

You probably also want to make sure that allow a switch back to the assigned primary path in the event of a failure of the primary:

# pvchange -S y /dev/dsk/cXtYdZ

See the man pages for 'pvchange' for more information.

Regards!

...JRF...

Re: Changing Alterante Paths.

Slawomir Gora — Thu, 15 Dec 2005 08:16:18 GMT

Hi,

To change it permanently (across VG deacivation/reactivation) you have to change the order in /etc/lvmtab by using vgreduce and vgextend commands - look at my previous reply.

Re: Changing Alterante Paths.

Devender Khatana — Thu, 15 Dec 2005 08:23:40 GMT

Hi,

The alternative has allready been provided.
Try this and should exist even after reboot.

HTH,
Devender