List,
So I've done a lot of physical standby database setups on single-instance
dbs. Not so many on RAC however.
Oracle gives the following guidance for a RAC physical standby:
(maximum # of logfiles +1) * maximum # of threads
The example given says:
This example uses two online log files for each thread. Thus, the number
of standby redo logs should be (2 + 1) * 2 = 6. That is, one more standby
redo log file for each thread
On our RAC we have 6 nodes and I'm going to replicate to a 4 node standby
RAC (though the DB only ever runs on 2 nodes of each)
So, on the primary I have :
24 Groups and 6 Threads. Each thread# has 4 Groups. The total # of
logfiles is 24.
So Oracle's math here would be (24 + 1) * 6 or 150 standby logfiles.
That doesn't seem right to me.
Seems like it ought to be ((24 / 6) +1 ) * 6 for 30 standby logfiles
That would give 1 additional standby logfile per thread.
Is that correct?
Though I'm not sure what to do with the odd # threads *AND* the primary
runs on thread# 5 & 6 while the standby will be on thread# 3 & 4 though
maybe Oracle can automagically resolve/transmit the changes even though the
thread #s might be different?
The doc for this (that I see repeated across multiple blogs) is
https://www.oracle.com/technetwork/database/features/availability/maa-wp-10g-racprimaryracphysicalsta-131940.pdf
(which is 10g but the advice should generally be true even if the math is
incorrect)
Chris
