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

From: David Barbour <david.barbour1_at_gmail.com>
Date: Thu, 26 Dec 2013 15:51:28 -0600
Message-ID: <CAFH+ifcXtyR2EGnRAGWVcsX=ZJivA_zJsQ4orEA2uT7PX3UA2A_at_mail.gmail.com>



Fail-Over - not as in standby, but as in TAF for instance/node down. Unfortunately I don't have the option of putting all the storage on one platform or another. The VMAX lease is coming due and 'something' is going to change. Meanwhile, we've purchased Compellent and the dictate is the new application WILL be on Compellent. AND it's supposed to be a three-node RAC, but they've only purchased two servers. Node 3 of the existing RAC has a light enough load to take up the slack if Node 4 or Node 5 goes down. Or Node 1 or Node 2 for that matter. Or Node 2 and Node 5. You get the drift.

Okay - I guess I've gotten enough feedback on this. Thanks. It's stimulated some thinking after too much food yesterday. I've got a couple of ideas. I'll let you know how it does or doesn't work out.

On Thu, Dec 26, 2013 at 2:46 PM, Mark W. Farnham <mwf_at_rsiz.com> wrote:

> My first question is what do you mean by fail-over?
>
>
>
> 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, Id 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 wed 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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Received on Thu Dec 26 2013 - 22:51:28 CET

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