topic Re: Is the Quorum Server required for a 2 node cluster? in Operating System - HP-UX

Is the Quorum Server required for a 2 node cluster?

Greg OBarr — Thu, 12 May 2005 13:12:00 GMT

I am migrating our production environment from 2 rp5450s running HP-UX 11.00 with Service Guard A.11.09 to 2 rp5470s with Service Guard A.11.15.

In our current version of Service Guard (11.09), there no "Quorum Server", but there is one in the 11.15 version, and it appears to be a requirement to run the cluster. The instruction also indicate that the quorum server needs to be located on a system other than one of the 2 cluster nodes.

Is this true? Why can't I just use the cluster lock on the VGs like I'm doing now and skip the quorum server? I don't want to have to stop and setup another system just to run the quorum server.

Thanks in advance....

-greg

Re: Is the Quorum Server required for a 2 node cluster?

melvyn burnard — Thu, 12 May 2005 13:15:30 GMT

Greg
11.09 of Serviceguard did not have the Quorum Server option, but 11.15 does.
You can still use a cluster lock disc if you wish.
see page 10 of http://docs.hp.com/en/B3935-90063/B3935-90063.pdf

Re: Is the Quorum Server required for a 2 node cluster?

Silver_1 — Thu, 12 May 2005 13:22:16 GMT

Hi,

In HP UX there is not concept like quorum server (which is in Linux).

Here you can take one of the shared disk as the vglock disk and mention it in the config file.

Preferably the lock disk can be a small LUN in the shared SAN.

Tx,

Nair

Re: Is the Quorum Server required for a 2 node cluster?

Greg OBarr — Thu, 12 May 2005 13:32:21 GMT

Thanks Melvin. I'm not seeing in the documentation that the quorum server is an "option". I'm looking at the document "Managing MC/ServiceGuard" at this link:

http://docs.hp.com/en/B3936-90073/B3936-90073.pdf

Is there any other documentation available on setting up version A.11.15 without using the quorum server? Or is it really no different than setting it up in version A.11.09? I don't want to use the quorum server if I don't have to, but this will be a production system and I don't want to sacrifice any useful functionality or stability.

Re: Is the Quorum Server required for a 2 node cluster?

Steven E. Protter — Thu, 12 May 2005 13:40:04 GMT

No, I just did a SG 2 node cluster without a quorum server. Used a lock disk instead.

Quorum server is actually a seperate download. It can be installed on an HP-UX box or a Linux workstation. The quorum server software is free at http://software.hp.com

SEP

Re: Is the Quorum Server required for a 2 node cluster?

melvyn burnard — Thu, 12 May 2005 14:04:37 GMT

Greg
The Release Notes on page 10 state that Quorum Server is available as an alternative to the Cluster Lock Disk.
If you wish to use this, then you need to specify the -q on the cmquerycl command line.
If not (as in your case) it is a standard 2 node cluster set up, have the shared VG available and active on one node, do the cmquerycl and it should allocate a lock disc for you

Re: Is the Quorum Server required for a 2 node cluster?

Greg OBarr — Thu, 12 May 2005 14:06:06 GMT

Thanks everyone! I'm going to start configuring without the quorum server.

Re: Is the Quorum Server required for a 2 node cluster?

Kent Ostby — Thu, 12 May 2005 14:54:48 GMT

Greg --

You can also look at the following document in the ITRC which discusses differences between the lock disk and the quorem server.

UMCSGKBRC00012642

http://www1.itrc.hp.com/service/cki/search.do?category=c0&mode=id&searchString=UMCSGKBRC00012642&searchCrit=allwords&docType=EngineerNotes&search.x=21&search.y=7

Lock disk is a good solution for a basic cluster set up .

This document shows cluster lock disk concepts:

UXSGKBAN00000282

http://www1.itrc.hp.com/service/cki/search.do?category=c0&mode=id&searchString=UXSGKBAN00000282&searchCrit=allwords&docType=EngineerNotes&search.x=21&search.y=7

Re: Is the Quorum Server required for a 2 node cluster?

Matthew Ghofrani — Fri, 13 May 2005 08:21:05 GMT

Quorum Server is only required if you have more than 4 nodes in your 11.15 Ver. of MCServiceGuard.
Note of caution: Setting it up is very simple but your quorum server plays an important roll when a node wants to join the cluster, meaning you should treat that Q server just as importatnt as your prod servers in the cluster. Also place them into their very own internal hub (including your Q server)

Matthew from Boston

Re: Is the Quorum Server required for a 2 node cluster?

Stefano_65 — Fri, 13 May 2005 08:24:46 GMT

Quorum Server is not required for a 2 node cluster. You can use a shared disk as Cluster Lock. Only for 4 node cluster you need a Quorum Server.
s.

Re: Is the Quorum Server required for a 2 node cluster?

Uwe Zessin — Fri, 13 May 2005 09:09:58 GMT

Just FYI:
there are valid configurations that do not allow a lock disk on a HSG-controller based Fibre Channel storage.

Re: Is the Quorum Server required for a 2 node cluster?

Serviceguard for Linux — Fri, 13 May 2005 13:15:57 GMT

Read Melvyn's reply. It is correct. A Quorum me3chanism is required for any cluster of 4 nodes or less. That quorum mechanism can be either the Quorum Server or the Lock Disk. Just amke sure that they are supported in the configuration you have (both HW and SW).

If you want a quorum for greater than 4 nodes then quorum server is the only alternative. If you have greater than 4 nodes, a quorum is not required UNLESS you have a split site type cluster. Look at the docs for those for the details.