RE: Questions consolidating databases onto RAC Cluster

From: Powell, Mark <mark.powell2_at_hpe.com>
Date: Thu, 28 Apr 2016 19:12:26 +0000
Message-ID: <1E24812FBE5611419EFAFC488D7CCDD132B0D1E1_at_G4W3290.americas.hpqcorp.net>



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_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Mark J. Bobak Sent: Wednesday, April 27, 2016 5:09 PM To: Chris Taylor <christopherdtaylor1994_at_gmail.com> Cc: ORACLE-L <oracle-l_at_freelists.org> 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_at_gmail.com<mailto:christopherdtaylor1994_at_gmail.com>> 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

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http://www.freelists.org/webpage/oracle-l Received on Thu Apr 28 2016 - 21:12:26 CEST

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