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General questions on Serviceguard (planning an installation, and teething problems).

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Iain Soedring
Occasional Advisor

General questions on Serviceguard (planning an installation, and teething problems).

Hi,

I'm looking at using Serviceguard to create a simple High-Availability cluster of Apache httpd servers.

Looking at the documentation on this product, there's a lot of talk about shared disk volumes, SAN etc.

What I want is just three httpd servers configured so that if the 'master' server fails, one of the others will take over, using a reallocatable IP address. This is all I want, no shared volumes, no quorum server, nothing else.

Looking at the hp documentation it appears Serviceguard may be too 'heavyweight' for my needs.


My questions are:
1. Is my simple web server simple possible with Serviceguard, or do I need to create shared disk volumes?

2. I have version 11.17, are there any fixpaks I need for this? I keep getting 'Node refusing Serviceguard communication', despite following all instructions on working around not having identd running, setting up cmlnodelist etc.
7 REPLIES
Ivan Krastev
Honored Contributor

Re: General questions on Serviceguard (planning an installation, and teething problems).

You can create Serviceguard cluster with packages without shared disk, but you will need a quorum server for cluster locks.

No problem to create the package without shared storage - in package control files just add httpd stop and start scripts.
When package fail from one node to another it silmply will do the following:
node1: stop httpd
node1: remove shared IP
node2: apply shared IP config
node2: run httpd


regards,
ivan
Iain Soedring
Occasional Advisor

Re: General questions on Serviceguard (planning an installation, and teething problems).

Thanks Ivan, but will I still need a quorum server if I have three nodes?
Ivan Krastev
Honored Contributor
Solution

Re: General questions on Serviceguard (planning an installation, and teething problems).

Quorum server is used as a cluster lock no matter how many nodes you have.

It is recomended for more than 3 nodes cluster and in your case (you don't have a cluster lock disk) it is mandatory.

See more info about quorum here - http://docs.hp.com/en/B3936-90078/ch01s06.html

regards,
ivan
Thomas J. Harrold
Trusted Contributor

Re: General questions on Serviceguard (planning an installation, and teething problems).

If you have an extra Linux server (or an older Intel server that could host Linux), you can run quorum services on that node.

Alternatively, you can create a 2 node cluster and have the 3rd node run your quorum service.

QS is supported on RedHat, Suse, and HP-UX. It would be nice if HP would support it on Windows as well. On second though, maybe not... :)

-tjh
I learn something new everyday. (usually because I break something new everyday)
Colin Topliss
Esteemed Contributor

Re: General questions on Serviceguard (planning an installation, and teething problems).

I wouldn't bother with ServiceGuard - HP are dropping it for Linux.

Have a look at RSF-1, LifeKeeper, or even the cluster technologies for your distribution.

RSF-1 certainly doesn't use lock-luns or a quorum server.

Discontinuation notice can be found here:

http://h18026.www1.hp.com/solutions/enterprise/highavailability/linux/serviceguard/discontinuance.html
Thomas J. Harrold
Trusted Contributor

Re: General questions on Serviceguard (planning an installation, and teething problems).

Any clustering product that doesn't use lock luns or some sort of cluster arbitration should be considered risky at best.
I learn something new everyday. (usually because I break something new everyday)
Colin Topliss
Esteemed Contributor

Re: General questions on Serviceguard (planning an installation, and teething problems).

Cluster control can be done without the need for lock-LUNs or a quorum server. That just happens to be the way ServiceGuard does it.

Life-Keeper uses SCSI-reservations on the LUNs under its control - however it requires a partition on the LUN to achieve this. This is fine for new clusters - but a real pain for existing ones where you need to migrate (I have a few, and they are large clusters - I have one with 14TB of storage for example).

RSF-1 doesn't - so its a bit more of a challenge. But it does make migration easier.

Not sure about VCS - haven't got that far in my quest for an SG replacement yet.....