I agree with Mark Bobak. We have ran as many as 13 side by side RAC databases
on a server without issue. As long as your server has capacity you can do it.
Where some people think this is a problem is if your server, especially the
disk, is showing heavy load in figuring out where the load is coming from. The
Top/Topmonitor and other UNIX/OS utilities can generally pin-point where the
load is coming from and then you tune the instance as normal. Disk tools can
identify where the IO is coming from if not obvious from the OS utilities.
Generally speaking finding conflicting demand from the database instances is
not an issue.
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On ;
Behalf Of Mark J. Bobak
Sent: Wednesday, April 27, 2016 5:09 PM
To: Chris Taylor <christopherdtaylor1994@xxxxxxxxx>
Cc: ORACLE-L <oracle-l@xxxxxxxxxxxxx>
Subject: Re: Questions consolidating databases onto RAC Cluster
I'm not currently running any RAC at my current employer.
However, I've run RAC clusters with multiple databases on them in the past with
no issues.
I'd argue that the considerations and trade offs are similar to single
instance, in terms of memory and CPU resources and availability. If you have
multiple schemas that support multiple applications, and that DB goes down, all
your applications are down. Question is, do you have enough spare memory and
CPU to run multiple instances on a node?
But, there's nothing inherently bad about multiple DBs on a single RAC cluster.
At least, no more so than you'd expect. When you run into performance
problems and/or resource issues, you'll have multiple places to look.
Of course, regardless of how many DBs in your cluster, you *must* run only one
GI Home, and its version must be greater than or equal to the highest version
DB.
Hope that helps,
-Mark
On Wed, Apr 27, 2016 at 4:13 PM, Chris Taylor
<christopherdtaylor1994@xxxxxxxxx<mailto:christopherdtaylor1994@xxxxxxxxx>>
wrote:
After doing some research, it appears that common wisdom is to NEVER have 2
different RAC databases sharing the same cluster.
For example:
2 Node RAC with more than one RAC DB
Is this still true?
Reference:
https://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:1855800700346081917
If you have a RAC DB on 2 nodes, but the nodes are only 10% utilized, is the
only best option really to migrate the schemas into the existing RAC DB instead
of adding separate RAC DBs to the existing cluster?
Is there some other option here that I'm missing to take advantage of the spare
resources on the RAC cluster hosts? (Other than 12c and multi-tenant)
Chris
