RE: Multiple DBs on One RAC - Adding New Nodes and Different Storage

IF someone asked me about adding nodes to host a new application to a shop with a new disk farm from a different vendor than the existing one, I'd be inclined to keep them separate and make this a standby recovery (home rolled or possibly passive or active dataguard, depending on your licenses and requirements for time until application use resumes) rather than increasing the complexity of the existing ASM complex.  

You would need to be able to write from lgwr or arch to some location that the nodes on the existing cluster can see, but that seems a lot less demanding a storage task to me than fully integrating new storage and nodes into ASM. And since they would fail separately, I think your overall availability would increase. Quite possibly the two new nodes might serve as standby recovery targets for the existing cluster in case that ASM complex fails.  

On the other hand if the peaks and valleys of your applications across time are such that some might benefit from 5 nodes enough of the time to make it worth the trouble, then I think the best way to go is to fully integrate the ASM requiring, as Tim wrote, at least visibility to the configuration and coherency bits of ASM. You might make disk groups exclusively on the new storage, but at least one node of the first three will need to be able to see that disk to facilitate rac instance type fail over (as opposed to standby failover).  

To make a real recommendation we'd need to know a lot about your mission, goal, and resources.  

mwf  

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of David Barbour
Sent: Thursday, December 26, 2013 2:23 PM To: oracle-l mailing list
Subject: Multiple DBs on One RAC - Adding New Nodes and Different Storage  

Merry Christmas (to those of you who celebrate), Happy Holidays (to those who may not but have something going on - including New Year's), and Good Afternoon:

We are currently running a 3-node RAC on RHEL 6.3(version 2.6.32-279.22.1.el6.x86_64), Oracle 11.2.0.3.0 on ASM. Storage is fibre-connected EMC VMAX. Cluster cache communication is handled via Infiband. We are adding a new application and two nodes. The question arises with the storage. We're putting the new application on a Dell Compellent SAN. Also fibre connected. The plan is to make the 2 new nodes the primary nodes for this application, and make node 3 of the current cluster the fail-over.

Can anyone who has used multiple different SANs before provide any hints/tips/tricks/pitfalls?

Will we have to serve the current EMC Storage to the new nodes? I don't see why as we're not expanding the number of instances of the currently running application. But we will have to zone the new storage to connect to the third node of the current cluster. Any thoughts on how to install this new application? I don't really want instances of it on Nodes 1 & 2 at all. If I make Node 3 the master node and install from there, I should be able to pick Nodes 4 & 5 on which to create the other new instances.

Any thoughts?

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