Oracle RAC without OS Cluster

[Shivkumar]

Hi,

Is it possible to configure Oracle 11g for RAC without deploying Operating System Clusters ?

If yes then how ?

Thanks,
Shiv

[Duncan Edmonstone · Accepted solution]

Yes you can - you use Oracle Clusterware. manuals for install on HP-UX are here:

http://download.oracle.com/docs/cd/B28359_01/install.111/b28259/toc.htm

However if you go down this route understand that:

i) You *must* use ASM for your database and flash recovery area - no filesystem support
ii) You will need to ensure that you have native MPIO for raw disks, as ASM can't do MPIO - and you *can't* use LVM PVlinks - so you'll need to be on 11.31 with supported storage or on earlier versions hgave some MPIO software like HP Secure Path, HDS HDLM, or EMC PowerPath
iii) You'll need to provide network resilience in the form of APA as well, as Clusterware can't do this.
iv) Clusterware also doesn't monitor cluster interconnect
v) Clusterware has inferior hung-node detection to Serviceguard as it isn't kernel integrated - just do a google search on "oprocd toc" for many examples
vi) Integation of 3rd party apps is weak in Clusterware - for example no IO fencing is provided for non-ASM storage.

... I could go on...

HTH

Duncan

[Shivkumar]

Then why Oracle recommend Clusterware ?
Is there any reason behind it and oracle wants to push its own home grown inferior technologies ?

Seems like Operating Systems cluster like Service Guard is much better option ??

[Sajjad Sahir]

Dear Shiv

Service guard will get the control up to u logical volume, which means it doesn'thave any control over u oracle

thanks and regards

Sajjad Sahir

[Heironimus]

Having seen both solutions used in the past, I would say that putting Oracle under OS clustering feels like more of a "home grown inferior" solution than RAC does. A complete HA solution can easily requires both pieces, though.

If you use OS clustering to manage Oracle without RAC then you can't do transparent failover. An OS cluster system has to detect the failure, bring up the service IP, mount the filesystems (which will be dirty if you crashed), and start the databases (which will also be dirty if you crashed). While that happens your database is unavailable. When it comes back all the apps have to reestablish their connections, which some apps don't handle very well.

RAC is an active-active cluster and the Oracle client handles failover internally. RAC replaces the simple OS-level process failover with application-level clustering for failover and higher performance (multiple RAC nodes can process queries simultaneously), but you have to supply your own shared storage and network redundancy. As mentioned, RAC without an actual cluster filesystem means using raw volumes. Raw volumes are a nuisance to manage for everybody involved, and they tend to waste expensive SAN space.

RAC licensing and support is also very expensive, and it's much more complex for the DBAs than standalone Oracle servers. RAC is a good example of being able to have all the availability and performance you can pay for.

[Steven E. Protter]

Shalom,

Service Guard is not required to run Oracle 11g RAC.

SEP

[Mel Burslan]

> Then why Oracle recommend Clusterware ?
> Is there any reason behind it and oracle
> wants to push its own home grown inferior
> technologies ?

I am assuming this is a rhetorical question but regardless I will humor you and myself and answer.

Q. Why ?
A. Money !

Simple enough ? They want to make money by suggesting you license Clusterware from Oracle instead of paying HP for serviceguard. Also the ongoing support fees. It is the gravy train. They do not care if your enterprise suffers, as long as you pay Oracle their fees and they promise you that shortcoming will be addressed in the next release or two. :)

[Shivkumar]

If Service Guard is not required to run Oracle 11g RAC then it means it would use raw file systems as clusterware may not have feature for providing cluster file systems. Right ??

[Rahul Sharma_4]

Yes - installing only oracle clusterware wont provide you the filesystem. In that case you will have to settle with ASM based-disks.
http://www.oracle.com/technology/products/database/asm/index.html
Third-party clustering was a pre-requisite for oracle RAC only until oracle 9i.