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RE: Shared server tuning

From: Sentell, Aaron <aaron_sentell_at_tempe.gov>
Date: Wed, 9 Jun 2004 16:53:33 -0700
Message-ID: <FB764361B1966B458DD9B88713EB22350CAC8AA9@mercury.tempe.gov>


First of all, thanks to everyone for their responses so far. Your input is very much appreciated.

So now I'm talking about and considering changing this instance over to use dedicated connections, but before I charge ahead "blindly" I would like to have a valid reason for doing this rather than just crossing my fingers and hoping MTS is the problem.

  1. Is it possible for MTS to be causing problems even when all the v$ views I query don't show anything? I've checked all the MTS diagnostic views that Metalink recommends taking a look at, and I don't see anything that sticks out.
  2. Virtual circuit status wait must be some kind of indicator although Statspack doesn't list it in the Top 5 wait events when oraperf.com does (for the same spreport output). From Metalink, "Virtual Circuit Status is a wait event for the dispatcher to communicate with the shared server." So if the wait time is "high" for this event and I still have not hit my max_shared_servers limit, what is the dispatcher waiting for? Is it waiting for another shared server to be dynamically created? Even if it is, we are only creating/destroying an average of five shared servers per day. That can't account for all the wait time. What gives here?
  3. I know there is a bug (#2913826) for MTS sessions hanging. I looked at it on Metalink, but it is in a suspended state. I see at the bottom it says, "Basically the patch is working", but it doesn't state which patch, and I don't see a way to look up a patch based on bug number. How do I know if I have hit that bug in the first place? There's just not much to go on out there.

Any input would be greatly appreciated.

Thanks!

Aaron

-----Original Message-----

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Sentell, Aaron
Sent: Tuesday, June 08, 2004 2:44 PM
To: oracle-l_at_freelists.org
Subject: RE: Shared server tuning

At the most I would say we would be serving 30 concurrent users. Until I attended IOUG Live in Toronto, I had always thought that MTS was the way to go. After all, it simplifies things, right? No! From what I learned in Toronto, I am going to do my best to avoid MTS from now on if I do not absolutely need it. I am going to look into configuring this instance to use dedicated connections.

-----Original Message-----

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Mercadante, Thomas F
Sent: Tuesday, June 08, 2004 12:07 PM
To: 'oracle-l_at_freelists.org'
Subject: RE: Shared server tuning

Aaron,

You can get the 90% performance gain if you are not experiencing a known MTS bug that exists in 8.1.7.2. Since you are using 9.0.1.3, I suspect that you may be sharing the same pleasure I am.

The MTS bug causes a 60 second delay in processing. Something about a timeout. I don't get it every time, but we had to work things around a bhit to avoid it.

Look in Metalink for MTS bugs for your release.

If you can switch to dedicated servers, do it. How many concurrent users do you expect to serve?

Tom Mercadante
Oracle Certified Professional

-----Original Message-----

From: Sentell, Aaron [mailto:aaron_sentell_at_tempe.gov] Sent: Tuesday, June 08, 2004 2:48 PM
To: oracle-l_at_freelists.org
Subject: Shared server tuning

I have a six-month-old Oracle 9.0.1.3 database that is using shared server connections. Users are complaining about system slowness sporadically throughout the day, but I don't see any CPU, i/o, or network-related issues with the server itself. I have run a few Statspack reports through oraperf.com, and they all say that I can get a 90%+ gain by tuning MTS. In addition, in the waits section, virtual circuit status is by far the event with the most wait time.

I have checked the v$shared_server_monitor view, and nothing raises a flag with me. SERVERS_HIGHWATER has never come close to approaching MAX_SHARED_SERVERS. There are some servers started and terminated throughout the business day (3-4), but I don't think this would causes the symptoms I am seeing.

Personally, I am tempted to switch to using dedicated connections. Our Peoplesoft Financials and HR databases use this, so I doubt this application would have a problem with it.

Does anybody have any thoughts or ideas?

Thanks,

Aaron Sentell
Database Administrator
City of Tempe, Arizona



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Received on Wed Jun 09 2004 - 18:50:29 CDT

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