RE: Standby Database performance

From: Storey, Robert (DCSO) <"Storey,>
Date: Wed, 23 Nov 2011 17:25:35 +0000
Message-ID: <33B09BA255BD7142B217C2C0A0D0183401C79A_at_DCSOSVMS02.dcso.org>

Just curious on my part. When you say the standby is lagging, how much of a lag are we talking about? Do you ship the logs as they are created, or do you batch them up?

In just doing the math, if I'm right, your generating about 1250 logs in a day at the rate of about 53 an hour? So you are popping an archive log every minute? I got those numbers at 2.5tb = 2500GB. 2GB archive log equates to 1250 logs at that size, so about 53 an hour if you are doing 1250 logs in a day. That's an archive log every minute

I don't think you can tune the application time that much. I thought that was a product of the processing speed of the hardware and the limitation of how fast oracle can apply redo. Maybe I'm wrong, but I think if 45 seconds for 2gb of redo application seems pretty decent.

What is the implication of the standby lagging? Are you using it for real time reporting? How long does it take to ship the logs to the new system. I guess I'm wondering that if it takes you 2 minutes to ship the log to the standby, then 3 other logs are going to get generated. From just a pure shipment standpoint, how can you ever catch up?

Not helping your problem, sorry, but I'm curious as to the overall picture of how the lag is occurring and where.

Thanks

-----Original Message-----
From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of kapil vaish Sent: Wednesday, November 23, 2011 8:47 AM To: cicciuxdba_at_gmail.com
Cc: oracle-l_at_freelists.org
Subject: Re: Standby Database performance

Thanks Alan for your comments. Our standby is lagging behind even with this apply rate and we have to often use RMAN to sync it  up.  
THanks
Kapil

---

From: Guillermo Alan Bort <cicciuxdba_at_gmail.com> To: kapilvaish1_at_yahoo.com
Cc: "oracle-l_at_freelists.org" <oracle-l_at_freelists.org> Sent: Wednesday, November 23, 2011 5:53 AM Subject: Re: Standby Database performance

<disclaimer>this is a strictly unhelpful comment </disclaimer> I'm curious as to why you want to further reduce the apply time. Are you experiencing a delay in the standby because it takes 45 seconds to apply the archivelogs?

One of the key concepts of tuning in knowing when to stop, so perhaps if you are experiencing no problems with this apply time it's time to leave it be and move on to the next problem (there's always a next problem... otherwise life would be boring)

hope that wasn't too unhelpful
Alan.-

On Tue, Nov 22, 2011 at 4:23 PM, kapil vaish <kapilvaish1_at_yahoo.com> wrote:

>
> Hi Guys ,
>
> we have physical standby database for one of our biggest database. Scripts
> ship the archived log to standby server and then using parallel 32, manual
> recovery is performed (thru scripts) . Archived log size is 2 GB and daily
> production archive generation is aorund 2.5 TB. We are trying to increase
> performance on our standby database. We tried tuning various standby
> related parameters and IO, maximum apply rate we could achieve is 45 sec
> per archive log.  Can you suggest any other tunings you may have seen in
> your environments ? any pointers are appreciated ..
>
> thanks
> kapil Vaish
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> http://www.freelists.org/webpage/oracle-l
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>
>

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Received on Wed Nov 23 2011 - 11:25:35 CST