Re: Why extra standby redo log group?

From: Fuad Arshad <>
Date: Sun, 5 Apr 2009 09:19:23 -0700 (PDT)
Message-ID: <>


5,2993939164,1,539739,1258291200,512,YES,ACTIVE,124541122419,4/5/2009 11:15:20 AM,124541122522,4/5/2009 11:15:20 AM
6,2993939164,1,539738,1258291200,294810112,NO,ACTIVE,124540991837,4/5/2009 11:03:59 AM,124541122419,4/5/2009 11:15:20 AM

As you can see both are active but one is archived=yes the other is not sicne it is a realtime recieve . in a very busy environment you will see all unassigned as Active with one being used as realtime till time that the backlog is more than the standby redo logs.

  • Original Message ---- From: Yong Huang <> To:;; Martin Brown <> Cc: Sent: Sunday, April 5, 2009 9:39:09 AM Subject: RE: Why extra standby redo log group?

Martin, John, Fuad,

Thank you. When you have heavy transaction for a period of time, if you have n log groups on primary and n+1 SRL groups on standby, do you see all n+1 SRL groups used? That is, on the standby, do you see all, not just n, rows in v$standby_log under status column, alternately showing 'ACTIVE'?

I know if I manually switch logfile on primary, only n SRL groups will be 'ACTIVE' (the extra stays unused). I'll test by building a small data guard where primary is on a node with fast storage and standby with slow storage and create lots of redo.

Yong Huang

  • On Sun, 4/5/09, Martin Brown <> wrote:

From: Martin Brown <> Subject: RE: Why extra standby redo log group? To:,, Cc:
Date: Sunday, April 5, 2009, 8:46 AM

Totally agree. Our configuration has 8 primary nodes and (of course) only 1 standby node. For those that don't run DataGuard 10g, you can only have 1 active standby node. Normal log switches happen about 3 per hour. During peak times, our log switchs pick up speed and this configuration keeps up quite nicely.

> From:
> To:;
> CC:
> Date: Sun, 5 Apr 2009 14:33:16 +0100
> Subject: RE: Why extra standby redo log group?
> I would agree with what Fuad says, it is to ensure
that the standby can keep up with the primary. It is only a recommendation though and not mandatory
> John
> -----Original Message-----
> From:
[] On Behalf Of Fuad Arshad
> Sent: 04 April 2009 03:44
> To:
> Cc:
> Subject: Re: Why extra standby redo log group?
> Well in my case I've seem standby redo logs used
to cover for backlogs I.e Log switching is faster than the standby instance can perform       

Received on Sun Apr 05 2009 - 11:19:23 CDT

Original text of this message