RE: Oracle High Availability Question(s)

From: Scott Canaan <>
Date: Wed, 14 Feb 2018 20:39:39 +0000
Message-ID: <>

We are currently using Data Guard and we hate it. It's the only place we use it and we were never given any training on it, so we threw it together as best we could. Every time we have to do anything with it (including patching), we pray that it will recover and continue working.

What we have proposed is to go to Linux clustering instead, eventually going to Libvert, eliminating the Data Guard and moving the fault tolerance to the cluster. The app is not Data Guard aware, so when a failover does occur, the app stops working until someone manually points it to the other server and restarts it. Linux clustering would solve that problem.

RAC was mentioned as another alternative, so I've been looking into it, but everything I found showed all of the nodes pointing to one disk or disk array, which is not what we want. I've already said that if they want us to go with RAC, we will require training as we are not going to go into it blind like we did with Data Guard.

Scott Canaan '88 (<>)

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From: [] On Behalf Of Tim Gorman Sent: Wednesday, February 14, 2018 3:27 PM To:; Subject: Re: Oracle High Availability Question(s)

Whether you have RAC licensing or not, anyone is far better off deploying Data Guard for high availability.

Data Guard is designed for high-availability and disaster-recovery first and foremost. RAC is designed as a scalability solution first and foremost, and the only way Oracle gets away with marketing it as an availability solution is because RAC must include fault tolerance against node failure to even operate. RAC is wonderful and mature software, but using it for availability is an adaptation.

On 2/14/18 12:10, Hans Forbrich wrote:
You might want to look up 'stretch RAC'

One useful article is Oracle's wwhite paper

disclaimer: My opinion, not my employer's /Hans

On 2018-02-14 11:59 AM, Scott Canaan wrote: Currently, we don't have a license for RAC, therefore we aren't using it. We have one application in particular that is required to be available as close to 7 x 24 x 365 as possible. One other requirement is that the redundancy includes physical disk, with one set of disks in one location and the redundant set in another location. In looking at RAC, it appears that a shared disk (or disk group) is used which doesn't satisfy the second requirement. So far, I have not found a description of RAC that shows it using more than one disk / disk group for redundancy. What is the best way to accomplish the second requirement?

Received on Wed Feb 14 2018 - 21:39:39 CET

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