Status of online redo logs on the standby database

  • From: Christopher Reeve <topher_reeve@xxxxxx>
  • To: oracle-L@xxxxxxxxxxxxx
  • Date: Sun, 17 Jan 2010 08:01:15 -0700

Hello listers
My first post...
I have a data guard environment running on on solaris 64. I have had 
some performance issues, on the standby side of things, concerning the rate at 
which redo is getting applied.  Except for the disk subsystem, the box itself 
is bored.  So I'm trying to figure out how to reduce the physical I/O.  The 
environment itself is managed by the DG broker, and I have it set up to do real 
time apply, which works great most of the time, until we get to our batch 
processing periods, four times a month, then the standby begins to lag.  One 
way of reducing I/O, I have read, is to NOT multiplex the standby redo logs.  
Certainly makes sense, with all the ways of getting redo over.  While that did 
improve performance and reduce I/O, I'm still experiencing periods of lag.  Is 
that enough background information?  OK, on to the question...
With my situation, real-time apply, etc., I expected to see activity in 
v$standby_log, which I do.  But I didn't expect to see activity in v$log, which 
I do.  I have not seen any status here besides "CLEARING" and 
"CLEARING_CURRENT".  So is this normal?  If not, is this causing additional I/O 
that I can reduce further?


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