relative merits of serviceguard/SGeRAC/RAC

[Paul Senior]

I am a hpux sys admin working in a business where new clusters are currently at the design stage. I need advice on how people decide which clustering technology to adopt (out of serviecguard, SGeRAC, and RAC).

I have experience of supporting serviceguard clusters, have built an SGeRAC cluster, and supported the hpux o/s underlying RAC clusters, so some experience of all 3.
I understand that serviceguard monitors for failure of hardware components on a server in addition to key software processes, and that in the event of failure a node's packages (depending on config) tend to failover to another node in the cluster.
With SGeRAC I know you benefit from the load balancing of RAC due to it's ability to operate volume groups in shared mode, as well as have serviceguard monitoring of hardware components.
What benefits are there in using a RAC cluster on it's own (i.e. not SGeRAC) even if hpux is being used as the o/s and serviceguard is already used by a company?

I am after opinions as to the thought process you go through to decide which form of clustering to choose.
Are there any white papers which compare the 3 clustering options?
I assume factors such as cost (including licensing), failover time, the favoured technology of the system architect, in house support skills, existing clusters in the company, etc will play a part.

[Duncan Edmonstone]

Paul,

You're right, there's a lot to consider when deciding this sort of thing. I describe just a few of the things to think about in my post on this thread here:

http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=1227660

The method of storage you use will also come into it (no doubt as well as the preferences of your DBA - be careful there as sometimes Oracle have a tendency to push a very one-sided view on what to do when building a RAC cluster, based on the usually incorrect assumption that everyting anyone could want to implement is an Oracle database!) and you also need to think about integration with other management tools and ease of use for sysadmins, plus who's in charge of what (again DBAs often expect to be in control of Oracle CRS, but you need root priviliges for that - how does that sit with your audit and control governance?)

Maybe if you tell us more about what your specific requirements are, we can give more directed advice.

Internally in HP, there's certainly material on choosing between a HP and Oracle cluster stack, but much of this is considered proprietary so you won't find it posted on any web page.

Even once (and if) you've decided on a HP stack, there are more choices to make around storage configurations - as a starting point I'd advise you to have a look at the white papers here:

http://docs.hp.com/en/ha.html#Serviceguard%20Extension%20for%20Real%20Application%20Cluster%20%28ServiceGuard%20OPS%20Edition%29

Of course you can always contact HP directly, I'm sure we'll be happy to help you understand the implications of the decision - contact your HP account manager or reseller.

HTH

Duncan