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Re: Oracle WAN performance questions

From: Roger Crowley <>
Date: Fri, 26 Jul 2002 20:11:51 GMT
Message-ID: <>

Nick Palmer wrote:
> Roger and all others, thanks for the replies.
> Roger,
> We are using MTS, as the potential number of users connecting to this
> database is around 800. Is MTS slower than not using MTS ? I'm not sure
> about the dedicated or shared listeners but I can check on that. Does that
> have a performance impact as well ?

The following applies to Oracle8i (if that matters). I don't have 9i.

A lot of things contribute to a performance impact. MTS can be slower ... each process uses a chunk of memory (and if you have memory waits, that can cause problems). However, that being said, shared servers act like the network concentrators (multiplexors) of days gone by ... so there are fewer of them than dedicated servers. Since you have about 800 connections (I assume you mean concurrent connections), you'll see a BIG improvement if you use shared servers.

MTS assumes that each client is not overly talkative (network speaking, that is). In other words, MTS works best if a client sends Net8 packets, then waits a while (maybe while the user fills out a form), then sends another packet or two. The clients have to be the sort who are willing to share the channel. For clients with heavy network usage, you lose a lot of the benefit. It shines in environments where clients have a lot of idle time (our web-based app taxes Apache more than Oracle <g>).

MTS also changes where session-specific information is stored. Dedicated servers place the User Global Area (UGA, where session info is stored) in the Program Global Area; Shared servers place the UGA in the Large Pool of the SGA. So you might have to tweak a few init.ora parameters.

Sometimes MTS is not an option. Our firewall doesn't know anything about Net8 behavior (dispatchers setting up client "conversations" on a "random" port) ... so I have to use MTS and assign specific ports to the dispatchers so that our network people can let them punch thru the firewall.

> Also, what are the Net8 parameters that one can configure. Are they client
> side or server side ?

The tweaks are not specifically Net8 parameters. They're init.ora things like MTS_MAX_SERVERS (max number), MTS_SERVERS (inital number), MTS_DISPATCHERS (number of and connections for each), and so on. A good book you might want to look for is: Oracle Net8 Configuration and Troubleshooting by Hugo Toledo & Jonathan Gennick; O'Reilly; 2001. Chapter 5: "Multi-Threaded Server" contains a lot of useful info. If you don't play around with Net8 much, you could do like I often do and go to the bookstore and read a chapter or two. (Actually, I got tired of doing that and bought the book ... maybe why Borders Books doesn't mind people like me who treat it as a sort of "library" often.)

> (I know thats a lot of questions, so you only have to answer the ones you
> want, and I can do some more research on the others)
> Thanks.
> Nick

I'd write more ... but today is the last day my company is in their office spaces ... so I've packed almost everything in boxes and have to rely on my memory (my mom used to tell me I'd forget my head if it wasn't attached).

Roger Crowley Received on Fri Jul 26 2002 - 15:11:51 CDT

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