Changing Alterante Paths.

[Amit Manna_6]

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

[Slawomir Gora]

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

[Devender Khatana]

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

[RAC_1]

You can do that with pvchange also.
pvchange -s

[Devender Khatana]

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

#pvchange -s /dev/dsk/c4t4d1

HTH,
Devender

[Muthukumar_5]

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

[Arunvijai_4]

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

[Amit Manna_6]

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

[James R. Ferguson]

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...

[Slawomir Gora]

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.

[Devender Khatana]

Hi,

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

HTH,
Devender