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We have an Oracle 11gR2 RAC cluster with 4 nodes. 2 nodes are dedicated to one database that's devoted one application and 2 nodes are dedicated to a completely separate database that serves a completely different application. They got all put on the same cluster. Why? Nobody really knows anymore.

We're looking at changing hardware and OS's and such on two of the nodes for one of the applications. Since they're in the same cluster, we're concerned about how to do this without effecting the other two nodes (or if it can even be done). We're installing two much newer nodes on this database with much newer OSs and I'm not sure if it will even let us add it to the cluster with the newer OS.

As such, we'd like to split the cluster into two clusters? Is there any easy way to do this? They share one ASM instance, but all the files are obviously separate within that instance.

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  • Do they share the same diskgroups?
    – Mat
    Jan 9, 2014 at 16:28
  • No, they don't share diskgroups.
    – rfusca
    Jan 9, 2014 at 16:31

2 Answers 2

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We just did the same thing.

  • install software in new machines and configure different cluster
  • copy tnsnames.ora, orapwSID files to new machines and prepare pfile
  • you may need to add SID to /etc/oratab file on new machines
  • shutdown database on old machines
  • dismount ASM diskgroups on old machines
  • present LUNs to new machines
  • mount diskgroups on new machines
  • start database on new machines
  • configure database, instances, services using srvctl on new machines

Now you can unconfigure and remove old machines from old cluster. Of course Oracle version on new machines has to be the same as on old machines. Or it is possible to do upgrade right away on new machines.

You should test procedure of course. There are quite a few possible problems on the way.

The idea is that Oracle DB does not store anything in "cluster". All the data is in datafiles, controlfiles, redo logs and spfile. Which is stored on ASM can can be mounted on another server.

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Sounds like you dont really need one 4 node cluster. Remove the 2 nodes from the cluster: link Then form a new, seperate cluster from that 2 servers.

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