RE: Probably stupid question about sum of SGA sizes on NT server...

That depends on what you mean by "available". Is this when the system has reached a steady state before any Oracle's are started? And what else is the server doing? NT tends to be a little less predictable for memory usage than Unix, unless you have loads of memory in the system and don't mind the odd 10M either way. Are you using MTS? Do you have processes which will be using memory while the server is running, for example an IIS?

As an aside, on a recent project rather than have lots of instances on an NT machine, I used a single instance with a huge SGA, and a resource plan, different tablespaces etc. to divide up the machine's resources between the other users. This worked quite well, because if they had been separate instances it would have been harder to allocate the CPU and memory to favor different users at different times of day. (It was a publishing system that needed to support interactive data entry, queries, batch publication jobs, etc.)

There's a "LOCK_SGA" parameter in initSID.ora these days, which if set to true will lock the SGA into main memory if you platform supports it
(I can't remember offhand if NT does).

So, my advice is to fire up PERFMON, start your instances, and just watch what happens, then resize your SGAs as necessary.

g

-----Original Message-----
Sent: Thursday, June 21, 2001 1:26 PM
To: Multiple recipients of list ORACLE-L

Hi folks,

as the subject indicates, I feel really stupid asking this question, but here goes...

If I have several Oracle 8i instances running on an NT Server with, say, 256Mb of memory available, then does this mean that the sum of the SGA sizes
for all the instances, taken together, can't exceed 256Mb? As I say, it feels like a stupid question, but the phrase "virtual memory" keeps popping
into my head!

Paul

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Author: Guy Hammond
  INET: guy.hammond_at_avt.co.uk

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