DataGuard - Maximum Availability mode vs sync detection
- From: "Laimutis Nedzinskas" <Laimutis.Nedzinskas@xxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 19 Jan 2007 11:04:31 -0000
Is it possible to know if standby is synchronized with primary when DG
is configured in Maximum Availability mode?
As I understand - it is not possible.
If primary dies for sure(absolutely no access to any primary files) then
there is no way of knowing if it was operating in Maximum
Availability(meaning standby is in sync) or downgraded into Maximum
Performance mode(meaning standby is not in sync.)
What are possible solutions to this problem?
I see just one: some data of the primary db must survive the primary
crash.
For example, the fact that primary went into downgraded Maximum
Performance mode is recorded into background alert log. If we have
access to this log then we can find in what mode the primary database
operated just before the death. Alternatively, control file is the most
credible source.
The question is: what is the best way to preserve this critical primary
db data so that it is readily available for the third party which
decides the failover? I can think of some shared storage for both
control files and background logs.
Fyrirvari/Disclaimer
http://www.landsbanki.is/disclaimer
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