Originally posted by: dingdingfish

when i man varyonvg, it says:
The varyonvg will fail to varyon the volume group if a majority of the physical
volumes are not accessible
Q1, but i create a VG with 2 disks, create lv and fs in it, then disconnect one disk from storage.i have done varyoff and varyon many times, varyon always succeed, why?
Q2, when one disk lost, the VG is not varyoff automatically, why?
#AIX-Forum

Originally posted by: SystemAdmin

Generally Quorum requires more than 2 disks to work. For example in a VG with 3 disks if 2 disks fail then the VG will varyoff if 1 disk fails then the VG will stay varied on. Are your 2 disks mirrored? If so then you will never use quorum because losing 1 disk will mean that the system will still be able to access the data on the disk.

The AIX Certification Guide redbook goes in to more detail about quorum and eplains it alot better than me :o)
#AIX-Forum

Originally posted by: CRM

Two disks is the one scenario where you can get some different results.

Quorum has to have over 50% available so if you just had two VGDA's (one on each disk) if you lose either disk then you would close the volume group.

Once you get three plus disks you only get one VGDA per disk and Quorum works as expected but for two disks to keep over 50% the special case is two VGDA's on one disk and one the other.

You can see this with the command lqueryvg -Atp <VG_NAME>.

On my system with two disks in rootvg:

Physical: 00046142afb2a1e5 2 0
00046142b091ccfa 1 0
In the physical section you can see the number 1 and 2 next to the disks, there are two VGDA's on the disk ending e5 and one on the disk ending fa.

If you pull out the fa ending disk the volume group will stay open.

If you pull out the disks ending e5 the quorum should be lost and the volume group will close.

I am guessing you pulled out the one VGDA disk, try pulling out the other and see what happens.

regards

Chris
#AIX-Forum

Originally posted by: dingdingfish

yes, your guess is very accurate. now, when i disable the correct disk and varyoff it. it can't varyon with quorum. my Q1 is solved.
but even if the state of this disk is missing, it doesn't vary off automatically. don't know why.
#AIX-Forum

Originally posted by: CRM

Can you explain the steps a little more clearly please? Not sure I follow the below.

There are also some differences with the rootvg over other volume groups, is this the rootvg you are using?

regards

Chris
#AIX-Forum

Originally posted by: dingdingfish

1. mkvg -y emcvg hdisk1 hdisk2

emcvg

1. mklv -y fslv emcvg 50

fslv

1. mirrorvg emcvg

0516-1125 mirrorvg: Quorum requirement turned off, varyoff and varyon volume group for this to take effect.

1. varyoffvg emcvg
2. varyonvg emcvg

1. lqueryvg -Atp emcvg

...
Logical: 000b8f1d00004c00000001232b41b65d.1 fslv 1
Physical: 000b8f1d076d431e 2 0
000b8f1d076d4460 1 0
...

1. lspv |grep 000b8f1d076d431e

hdisk1 000b8f1d076d431e

now i remove hdisk1 from EMC storage, on AIX, i run cfgmgr, but this vg don't varyoff automatically as manpage of chvg -Q option described
#AIX-Forum

Originally posted by: tony.evans

You used mirrorvg, which turns Quorum off, as it said after you ran the command, or am I missing somewhere where you turned it back on?

"0516-1125 mirrorvg: Quorum requirement turned off, varyoff and varyon volume group for this to take effect."
#AIX-Forum

Originally posted by: dingdingfish

sorry, i missed a step. i really use chvg -Q y to set it to yes.
#AIX-Forum

Originally posted by: tony.evans

At what stage do you use the chvg, before or after you varied the VG off and on again?
#AIX-Forum

Originally posted by: dingdingfish

after
#AIX-Forum

Originally posted by: tony.evans

chvg -Q only takes effect after the VG is varied off and on.

So turn Quorum back on before you varyoff the vg.
#AIX-Forum

Originally posted by: dingdingfish

ok, you are right, the quorum changes to 2 after varyoff and on
#AIX-Forum