MCSG Lock Disk Question

[Khile Klock]

Hi Guys,

I have a 2 Node MCSG CLuster..
My Current Lock Disk is on my JBODS..

I have added an EVA3000, and need to get a 3rd Node added to the Cluster..

I need to move my lock disk from the JBODs to the EVA..

I have created a 1GB LUN to use for LOCK_VG, LOCK_PV, etc..

1) AFter creating the PV and VG
Do I need to worry about an lvol?
How do I ensure the VG is always available and active to one node or another that needs it?? Will putting the VG into the cmclconf.ascii file be enough?

2) I need to halt my cluster
cmcheckconf
cmapplyconf -C (with file showing NEW LOCK_VG and LOCK_PVs
cmruncl

Should this work??
I do not need to have any lvols in this VG, right??
I just ned to make sure the VG is available to all 3 nodes, and is active somehow to one node or another.. (What does the activation, or can I vgchange it to sharable to all 3 nodes..??)

Thanx'
Khile Klock

FYI, for what it is worth.. currently my LOCK_VG is the first VG in one of my packages... but I need to move the lock disk, and not the package at the moment... and I woudl also like to separate the LOCK stuff from the package anyway....

Words of advice??

[A. Clay Stephenson]

My word of advice is to forget about a lock disk and substitute a Quorum Server. A small PC running Linux makes a nice QS and the QS software is free. You will find that this is a much more flexible solution than is a lock disk.

[Victor Fridyev]

Hi,

First of all, lock device is requested for two-node cluster only, so you don't need it in three-node cluster.
Secondly, my HP support did not recommend me to put lock device on EVA storage.

HTH

[Mel Burslan]

I second Clay's opinion here. We are weaning our lock disk using clusters one by one and moving them over to utilizing quorum servers.

Locks disks are a thing of the past. They are still okay to use but QS is more flexible and easier to use.

Also, when you change your lock disk or decide to use the quorum server, you will need to shut your cluster down and recompile the cluster binaries with the new tie-breaker mechanism/device of your choice. So changing it while your cluster and packages are up, is not an option

[Geoff Wild · Accepted solution]

Yes - you can use a lock disk on a 3 node cluster - all the way to a 4 node.

Second - you do not need a 1 GB LUN for it - it can be part of any VG that is seen by all nodes in a cluster (and it does NOT need to be activated)...

More on lock disks:

http://docs.hp.com/en/B3936-90079/ch03s02.html#d0e2120


Rgds...Geoff

[Thomas J. Harrold]

Should you choose to consider it, you can run a quorum server on any Linux (RH, Suse) node that is NOT part of your cluster, or on any HP-UX (11.11 or newer I believe) node that is not part of your cluster.

The application is downloadable from software.hp.com, and is very tiny.

It runs a daemon that listens for connections from cluster nodes, and can handle up to at least a hundred nodes. If one of your clusters ever needs to re-form, the quorum server will act as the arbitrator node.

I would highly recommend looking into this solution, since it sounds like you'll be making big changes to your existing cluster anyway.

-tjh

[Khile Klock]

The issue here is that we got the MCSG to reduce physical nodes... We've down sized everything onto the MCSG, and if I try to magically show a CPU addition, rather than a CPU reduction... I'm gonna hit soemone's radar.. :) I prefer (at this time), to NOT make myself that visible at this time..

I got the lock disk setup working, and verified with 'cminitlock -t'.

Thanx'for the opiniions tho!!
The biggest help was the answer to my "does it need to be activated" question...