RAC & DataGuard (Physical Standby)

Question

Hello all,
I'm trying to get a high level overview of how RAC & DataGuard would behave in the following configuration. I've written down my understanding of how things would work. Please correct me if I'm wrong.
1) 2 node RAC (Primary Database) with a single instance physical standby.
a) Same standby related init.ora parameters would have to configured on both primary rac nodes.
b) The redo apply service at the standby would merge the redo from the 2 threads from the primary and apply it to the standby to keep it in sync.
c) During switch over only one primary RAC instance should be up besides the standby instance.
d) During switch back again only one primary RAC instance should be up besides the standby instance.
e) During failover ofcourse both primary instances would be down which warrants the fail over.
2) 2 node RAC (Primary) with a 2 node physical standby
This where it gets complex and I'm not really sure how a,b,c,d,e would be in this scenario. Appreciate if you could shed some light on this and list what
a,b,c,d,e would look like in this scenario.
I'm assuming that only one instance in the standby RAC should be up when the standby is in RAC configuration for the redo apply to work.
Also, if there is a white paper that details step by step procedure for setting up the above 2 scenarios, please let me know. So far I was able to find only the MAA white paper but that was not very helpful. If you can prescribe a good book for RAC & DataGuard that would be great too..
Thanks for your help

Answer 1

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1) 2 node RAC (Primary Database) with a single instance physical standby.
a) Same standby related init.ora parameters would have to configured on both primary rac nodes.Usually rac nodes share their spfile on a shared diskvolume or through ASM. So they have identical DG parameter anyway
b) The redo apply service at the standby would merge the redo from the 2 threads from the primary and apply it to the standby to keep it in sync.Correct
c) During switch over only one primary RAC instance should be up besides the standby instance.
Sounds logical to me
Edit: In fact during normal operation both RAC nodes are up, so during switchover they are both active too
It is the configuration that matters. As soon as the standby is becoming primary, it might be that it talks only to one RAC node for its log-apply files
d) During switch back again only one primary RAC instance should be up besides the standby instance.That single was the only one running in step c.
e) During failover ofcourse both primary instances would be down which warrants the fail over.Correct. Keep in mind that during a failover the RAC config would be deconfigured from the DG setup and has to be added back again as standby.
You might have to take a look at: http://www.oracle.com/technology/deploy/availability/pdf/MAA_WP_10g_RACPrimarySingleInstancePhysicalStandby.pdf
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2) 2 node RAC (Primary) with a 2 node physical standby
This where it gets complex and I'm not really sure how a,b,c,d,e would be in this scenario. Appreciate if you could shed some light on this and list what
a,b,c,d,e would look like in this scenario.
I'm assuming that only one instance in the standby RAC should be up when the standby is in RAC configuration for the redo apply to work.
No. RAC primary to RAC Standby would mean both nodes are up on both side. PrimNode1 send its redo logs to StandbyNode1 and the same for PrimNode2 and StandbyNode2
Have a look here: http://www.oracle.com/technology/deploy/availability/pdf/MAA_WP_10g_RACPrimaryRACPhysicalStandby.pdf
HTH,
FJFranken
My Blog: http://managingoracle.blogspot.com
Edited by: fjfranken on 16-jul-2010 1:13