[Linux-cluster] Which lock manager to use on a 2-node GFS Cluster?

[Celso K. Webber]

Hi Riaan,

Thank for your excelent explanation!

Now I know I'll have to run an Oracle unsupported environment ... :)

Would someone please confirm if the environment suggested by Hirantha is 
supported by Red Hat?

* 2 GFS/RAC nodes;
* 2 DLM on RAC/GFS nodes;
* fibre channel external storage.

The above environment is what we usually encounter on our cluster 
projects. Sometimes Oracle Database is installed as active-passive (not 
a RAC Cluster). It would be useful to know if Red Hat supports it, even 
if Oracle does not.

Last question: does Oracle supports a 2-node cluster using DLM for 
Oracle Database (no RAC, no GFS) when used with RHCS?

Thanks again!

Celso.


Riaan van Niekerk escreveu:
> hi Hirantha
> 
> short answer: "No"
> 
> If you are willing to settle for "should work just fine" instead of 
> "certified by Oracle" you can try running DLM on 2 RAC/GFS nodes, then 
> "yes"
> 
> To have your solution certified/supported by Oracle, for a minimal 
> configuration you need 5 machines:
> a) 2 GFS/RAC nodes
> b) 3 external GULM lock servers
> 
> We also found these system requirements somewhat excessive (having more 
> lock servers than actual GFS-accessing cluster nodes).
> 
> more notes:
> - supported GFS with RAC is GULM only - DLM is not supported by Oracle, 
> because it is embedded by default.
> 
> - external lock servers - that means the the GULM service cannot run on 
> the nodes accessing the GFS. The 3 GULM nodes and the 2 GFS/RAC nodes 
> must be completely separate
> 
> - the reason for the separation of lock servers from GFS/RAC nodes is 
> that Oracle RAC is designed to be able to with a single node up, whereas 
> DLM  needs a quorum of 50%+1 to operate. Also, external lock servers 
> allow you to reboot any RAC node without causing the lock server to switch.
> 
> - specs for the locks servers are as entry-level as you can get for
> modern server hardware, e.g. 1CPU, 1GB RAM.
> 
> - Red Hat Knowledge base article for RAC on GFS: 
> http://kbase.redhat.com/faq/FAQ_78_3853.shtm
> It mentions GFS 6.0, (slightly out of date) but is just as relevant for 
> GFS 6.1 / RHEL 4). According to this article, "Red Hat does not charge 
> for Red Hat GFS nodes that are used only for the external lock server 
> configuration"
> 
> - the Cluster/GFS FAQ has some URLs for RAC on GFS:
> http://sources.redhat.com/cluster/faq.html#gfs_oraclerac
> 
> - MetaLink Note  329530.1 is the definitive source for what exactly is 
> supported by Oracle, w.r.t. RAC and GFS. Unfortunately it is only 
> available via Metalink.
> 
> Celso - answers to your questions below
...
-- 
*Celso Kopp Webber*

celso at webbertek.com.br <mailto:celso at webbertek.com.br>

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