topic Re: quorum in Operating System - HP-UX

quorum

newunix — Tue, 22 Jun 2010 06:47:06 GMT

if i am working in os and boot disk fails and if no quorun is acheived what will happen at that time.

will all the vg will be active ?

do i able to umount other mount points like /tmp in vg00 and oracle in vg45.

how can i act to that.

Re: quorum

AnthonySN — Tue, 22 Jun 2010 07:08:50 GMT

>>will all the vg will be active ?
it will work if the root disk is mirrorred.

Re: quorum

Duncan Edmonstone — Tue, 22 Jun 2010 08:06:57 GMT

if a volume group is unable to acheive quorum (>50% of the disks in the VG are available) then the VG will not activate.

So if a vg00 contains only 2 disks and one of those fails, at next boot thye VG will not activate.

We usually get around this by specifying an option to activate the VG even with low quorum by adding a "-lq" argument to the boot string. Exactly how this is implemented varies between HP9000 (PA-RISC) and Integrity (IA64) servers. Which do you have?

>> do i able to umount other mount points like /tmp in vg00 and oracle in vg45

The question makes no sense - if you don't have quorum on vg00, the VG won't activate and the system won't boot (unless you have specified low quorum)

HTH

Duncan

Re: quorum

newunix — Tue, 22 Jun 2010 11:31:36 GMT

my doubt is if i am working in os @ present and one disk goes fails will the server

reboot or what happens exactly @ the time.

suppose we have two disk mirrored but not given hpux -lq in auto file

so @ the time how all vg will be ?????

Re: quorum

Torsten. — Tue, 22 Jun 2010 11:33:08 GMT

@@@@@@@@@@@@@@@

If a disk in vg00 fails during OS is up and running, it stay up and running, no matter if booted in quorum mode or not.

Quorum mode come into play during VG activation only!

@@@@@@@@@@@@@@@

Re: quorum

newunix — Tue, 22 Jun 2010 11:34:10 GMT

at the time of disk fails and quorum not achieved do i able to access the all vgs at this condition that occured when i am working in server.

Re: quorum

Torsten. — Tue, 22 Jun 2010 11:35:13 GMT

question is answered above ;-)

Re: quorum

AnthonySN — Tue, 22 Jun 2010 11:38:45 GMT

as explained by torsten
you will not get any problem as such when u access you lvols incase of disk failure

Re: quorum

Torsten. — Tue, 22 Jun 2010 11:45:45 GMT

As said by Duncan:

quorum means, ">50% of the disks in the VG are available"

In case you have a VG with 2 disks, 1 failed, you have =50%, but not >50% - so activation will fail.

If you have a VG with 4 disks, 1 failed, you have 75%>50%; activation will work.

You can always overwrite the quorum check.

Is the quorum check useful?

IMHO it depends.

If you have let's say a VG00 with 3 disks, not mirrored (not unlikely some years ago with small disks!), you loose the data of the failed disk, but the system will try to boot.

If you overwrite the quorum check by default ("-lq"); so the system will always boot if the mirrored root disk is dead.

If the mirror partner is dead and the system does not boot because of the failed quorum check, you are alerted, manually overwrite the check and boot up.

This is IMHO the most useful use of the check.

And finally: Once the VG is activated; it remains activated even if you loose several disks. This does not mean you still can access all your data - this depends.

Re: quorum

P Muralidhar Kini — Tue, 22 Jun 2010 12:09:33 GMT

Hi newunix,

Check the following link -
http://forums2.itg1.itrc.hp.com/service/forums/questionanswer.do?admit=109447627+1259433598707+28353475&threadId=26178

Regards,
Murali