topic Re: primary path change in Operating System - HP-UX

primary path change

nanan — Fri, 14 Jul 2006 03:17:04 GMT

one of my systems using FC interfaces to XP128
the system is having 2 FC crads, while i checked the load balancing of I/O, i found that too many lvols assigned to one of them, so i wanted to change the primary path of some disks to alternative path.

I issued a command " pvchange -s /dev/dsk/cXtXdX" which was in alternative path device.

but i have experienced a strange thing that just within 10~13sec the path recoverd to the perviouse path.
i couldn't change the path

anybody can help me!!

the system has not any error messages

Re: primary path change

Peter Godron — Fri, 14 Jul 2006 03:44:22 GMT

Hi,
please have a look at:
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=1042661

Please only execute if you a certain what you are doing.

Re: primary path change

Sandy Chen — Fri, 14 Jul 2006 03:56:32 GMT

Hi Nanan,

You wanted both of the fibre to be used, then what you have to do is:

for example:
vg01
/dev/dsk/c10t5d0
/dev/dsk/c10t5d1
/dev/dsk/c10t5d2
/dev/dsk/c12t5d0
/dev/dsk/c12t5d1
/dev/dsk/c12t5d2

# vgreduce /dev/vg01 /dev/dsk/c10t5d1
# vgextend /dev/vg01 /dev/dsk/c10t5d1

and so on and so forth

regards,
Sandy

Re: primary path change

melvyn burnard — Fri, 14 Jul 2006 03:56:42 GMT

rather think about using
vgreduce
to remove a primary link, this makes the alternate link become the primary
and then use
vgextend
to add in the alternate link again

Re: primary path change

freddy_21 — Fri, 14 Jul 2006 03:58:57 GMT

pvchange is a temporary solution, if you reboot the server, your path will be back to original. vgreduce and vgextend is a permanent solution

thanks
freddy

Re: primary path change

nanan — Fri, 14 Jul 2006 18:57:11 GMT

Thanks for all answers!!

But i aready know what you suggested.

Actually what i am saying that after i chaged the path to the alternate one with pvchange commend, for a while chamged path become primary path, but soon recover to the original path automatically.

if i use "pvchange -s /dev/dsk/CXtXdX",
primary path changed and
the path is maintained till reboot the system, isn't it?

even i didn't reboot and any action to the system, as i mentioned,

Re: primary path change

sathish kannan — Sat, 15 Jul 2006 19:16:51 GMT

Hello Nanan,

What's is the error message you are getting on the syslog? Also did you try pvchange without any I/O i,e by deactivating the volume group?

Regards
Sathish

Re: primary path change

nanan — Wed, 19 Jul 2006 06:39:55 GMT

the messages inthe system's syslog are here!!

I've tested the same command on another systems and i got a different results:
recovering to the priveous path and never

could you tell me, the reason why there were such diffrent results...

thanks

Re: primary path change

nanan — Wed, 19 Jul 2006 06:41:03 GMT

the messages in the system's syslog are here!!

I've tested the same command on another systems and i got a different results:
recovering to the priveous path and never

it might be related with patch level or other things

Could you tell me, the reason why there were such diffrent results...

thanks

Re: primary path change

Khashru — Thu, 20 Jul 2006 00:37:57 GMT

Just do a vgreduce of the existing primary path. Then do a vgextend with this path. It will change the order of path.

Re: primary path change

nanan — Thu, 20 Jul 2006 16:47:37 GMT

vgreduce and vgextend can change the path