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I am comparing RAID 10 and RAID 5 configurations for Oracle database in order to determine the best choice in terms of performance for mixed workloads.

Is it possible to have 2 RAC node clusters and have one of them using the RAID 10 layout whereas the other one using RAID 5 layout?

This would make testing for things like "User load vs. Transactions per second for OLTP workloads" more fair and insightful..


Would it be feasible (for testing) to just use a single instance (ie. NO RAC) and run tests using RAID 5 layout and then change the layout to RAID 10 and re run the tests? What advantages/extra information does using RAC clusters when testing have?

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Is that going to be one cluster or two? –  NullUser Nov 5 '12 at 20:26
    
@NullUserException : two –  rrazd Nov 5 '12 at 20:34
1  
Are you asking whether two different nodes in the same cluster can use a different disk layout? Or are you asking whether you can have two different RAC clusters, one where each node has RAID-5 and one where each node has RAID-10? Or are you asking something else where you rebuild the cluster using RAID-10 between tests? –  Justin Cave Nov 5 '12 at 21:39
    
@JustinCave I AM ASKING IF its possible to have two different clusters (Each cluster happens to have two nodes), one cluster using RAID5 layout and the other using RAID10 layout. Please help... –  rrazd Nov 6 '12 at 19:24
    
OK. So, there is no relationship between the two clusters? They're not using the same database? –  Justin Cave Nov 6 '12 at 19:34
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up vote 4 down vote accepted

It appears as though you are asking whether you can have two instances of the same RAC (in an active-passive configuration) connected to different set of disks.

The answer to this question is no. To quote from the Introduction to Oracle RAC linked to in the comments of your other question:

An Oracle RAC database is a shared everything database. All data files, control files, SPFILEs, and redo log files in Oracle RAC environments must reside on cluster-aware shared disks, so that all of the cluster database instances can access these storage components.

This means that each node in a RAC must share the same disks, whether both are active or not. You could, I guess, rebuild the cluster between tests to have a different disk-layout but I don't see the point as you state in the comments that you have two clusters, i.e. at least 4 nodes.

Obviously, if you only have a limited set of disks you're going to have to rebuild anyway but if you want to do a proper comparison and you have two identical RACs set one up as a RAID-10 and the other as a RAID-5 and start testing.

Would it be feasible (for testing) to just use a single instance (ie. NO RAC) and run tests using RAID 5 layout and then change the layout to RAID 10 and re run the tests? What advantages/extra information does using RAC clusters when testing have?

As stated above I don't see the point. However, it depends on how you are going to use the RAC and what your intention was in getting two. There are 2 main reasons for using a RAC:

  1. The ability to have multiple servers accessing the same database.
  2. To enable fast recovery from a failure.

Whether you want to test with a single active node depends on your reason for obtaining this architecture. If you intend to run your RAC as an active-passive, i.e. one node is active and the RAC fails over to the passive node in the event of a failure in the active then by all means run your tests on a single instance (and ensure that you test whether it fails-over correctly)

If you intend to run the cluster as an active-active then it makes little sense to run tests on a single active node as this is not the configuration you intend to have.


To clarify based on your comment. You have two RACs. That means you have 4 servers, two sets of disks and two databases.

A simple diagram might look as follows:

Server 1 \
          --- RAC 1 --- Set of Disks 1 - Database 1
Server 2 /


Server 3 \
          --- RAC 2 --- Set of Disks 2 - Database 2
Server 4 /

The two RACS are in no way related so of course you can use two different RAID set-ups on them.

You can set them all up to use the same database but that isn't what you want to do.

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Thanks for all the information. I just read a paper by Dell where they described "For the performance tradeoff test, two Oracle 11G R1 (11.1.0.7) two‐node RAC clusters were deployed. One RAC cluster was deployed with RAID 10 layout and the other cluster with RAID 5 layout." So doesn't that mean that one cluster can use RAID 5 layout vs. other cluster use RAID 10?? –  rrazd Nov 6 '12 at 18:36
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Yes, of course. That's exactly what I say in my answer. Two two node clusters implies 4 servers. Each pair of servers using the same disks. You therefore have two sets of disks, each set of disks has one database. However, one cluster, that is 2 nodes / 2 servers accesses one set of disks. –  Ben Nov 6 '12 at 19:38
    
can you confirm that if I am using Quest Benchmark Factory TPC‐C with the aforementioned configuration, I will be able to generate 2 sets of data corresponding to RAID 5 and RAID 10 (simultaneously)? –  rrazd Nov 6 '12 at 20:33
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