Re: RAC and Data Guard Configuration Question

  • From: Martin Klier <usn@xxxxxxxxx>
  • To: chris.dunscombe@xxxxxxxxxxxxxxxx
  • Date: Wed, 07 May 2008 12:20:44 +0200

Hi Chris,

Chris Dunscombe schrieb:
> On the DR site we only have 3 nodes, we'd like 6 but 3 is all that we're going
> to get.
> The question is should we configure DR to have 1 instance per node (same as
> production) but this leaves only a total of 3 instances and hence 3 redundant
> UNDO tablespaces etc or have 2 instances per node?
> Also is it best practice to have the instance names on DR the same as in
> production.
> Any experiences, advice, "best practice" etc. for this is most welcome.

please keep in mind, that the standby database will only use one
instance for recovery, so you can use the power of the RAC on standby
side after a switchover only. In usual cases this should not be a
problem, physical standby recovery is rather cheap.

You don't need to count instances the way you explained - a RAC recovery
works very good on a single-instance standby system as well. Given, it
has enough power, of course.

Since the physical standby database is only in MOUNT state, the undo
tablespace usage does not count.

I assumed physical standby database as desired by you, should you prefer
logical stb, things are changing greatly: But in this case, I won't use
more instances per node than the production has.

Martin Klier

Usn's IT Blog for Linux, Oracle, Asterisk


Other related posts: