Re: RAC Oracle Upgrade Question

Rodrick Brown <rbrown[@]doitt.nyc.gov> wrote in message news:<2004092614114437471%rbrown_at_doittnycgov>...
> I know this is probably answered in the Oracle RAC FAQ or something but
> i'm not a DBA just suppot them :)
>
> When you need to upgrade RAC do you have to take the entire cluster
> offline ?

If you mean, 'can apply Oracle-supplied patches to one node of the cluster at a time', the answer in 9i is no. 'Rolling upgrades' as they are sometimes called are not possible: the entire cluster has to come down, be patched in one sitting, and then brought back up.

In 10g, apparently, this is not always the case, and some patches are allegedly rollable, or intended to be. Not sure if that's actually been tested by anyone yet in anger though.

> Can do you do standby/dataguard between 2 RAC clusters ?

Certainly. Single instance primary to single instance standby; single instance primary to RAC standby, RAC primary to single instance standby, and RAC primary to RAC standby are all eminently do-able.  

> Can you have different versions of Oracle in a RAC cluster ?

Of course not. You may have different instances, but you only have one database. So you only have one data dictionary. It's therefore completely impossible to have the one database accessed by both 9i and 10g instances (as a for-example). You might be able to do it technically with all sorts of clever tricks... but none of it would be supported by Oracle, and if it stayed up and working for longer than 5 minutes, it would be a miracle.

> Another questions can I have multiple databases ie multiple Oracle
> Homes on the clustered file system all running in a RAC configuration ?
> say 5 versions of Oracle binaries all 5 being clustered against 5
> systems each in their own RAC setup.

Yes. The shared disk is shared amongst multiple nodes, each of which has an instance accessing some database or other on that shared disk.

It would be perfectly legitimate to have a 4 node hardware cluster, for example, and have two nodes/instances managing the sales database and the other two nodes managing the, say, purchasing database.

I see Daniel has given a rather different answer, but I think his one illustrates what happens when you are a tad fuzzy about the distinction between a hardware cluster and an Oracle (software) RAC. That you buy a hardware cluster comprising, say, 8 nodes does not mean you have to use all 8 nodes to manage a single database. You may have a database which needs more than 1 instance to manage it, but 8 would be complete overkill.

It's therefore entirely understandable to have a need to 'partition' that hardware cluster so that smaller groups of nodes are used to manage particular databases within their own hardware requirements and limits.

I doubt you would install Oracle 5 times (though even then, there may be a need for both 9i and 10g to co-exist). But you could certainly have 5 sets of data files, 5 sets of control files and so on.

Regards
HJR
>
>
> Thanks alot.
Received on Mon Sep 27 2004 - 17:49:35 CDT