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SQL*Net Message to client/SQL*Net more data to client

From: Stephen Andert <>
Date: Tue, 29 Oct 2002 16:28:28 -0800
Message-ID: <>

We have experienced a sudden and dramatic decrease in performance sometime over the weekend (after Sat but before Monday 4 am). In following Gaja's tuning philosophy, I've found that the top 2 waits are usually (always 2 of the top 3) SQL*Net Message to client/SQL*Net more data to client. Everybody swears there have been no changes. SA's say no harware or kernel changes. AppDev say no code changes. DBA (me) says no database changes.

WAN folks say no WAN issues and ping is responding at expected speed. SA's say LAN card has had no errors during this time frame and is processing a good number of bytes but nowhere near it's capacity. The application has some very good timing points where there is no human element in response time, but there is a big "unknown" category that is a larger chunk of time than previously. We suspect that is machine wait time of some kind.

We just bounced the instance because someone wanted to try it and after being back up for 20 minutes, early indicators are that performance is back to normal. We'll see how long that lasts.

We have seen a few client sessions getting errors that indicate connectivity problems (listener not responding, etc) so we wrote a .com file that is repeatedly connecting to the database and will run overnight and stop if there are any errors.

Metalink search for SQL*Net waits gives both "tuning advice" and "you can't tune much" notes. I strongly suspect some kind of hardware failure, but don't know where since everyone involved says everything is working fine.

Environment Notes:
Tru64 5.1A (upgrade to A was done a few weeks ago) Compaq GS160 with 16 CPU's and 32 GB RAM (RAM is from memory, so that may be off)

Open VMS version 7.2
Client is 8.0.5

Any ideas on a next step for finding out the cause (solution) to this drop in performance???



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Author: Stephen Andert

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