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I am seeing a pooorly performing web app with a SQL 2005 backend. The db is on a w2k3 machine with 4GB RAM.

When I run perfmon on it I see the following.

Page life expectancy is low. Consistently under 300 while the Buffer cache hit ratio is always 99% +.

The target server memory is always 1618304 and the total server memory is always a number just below that. So it seems that it isn't grabbing enough of the available memory.

I have AWE enabled, with the lock pages right for the SQL service account and have set a maximum of 2.25Gb... but it doesn't go near that.

When I restart the SQL service the page life expectancy goes much higher, 1000+, and the total target memory starts at 0 and slowly works its way back up to the previous limit.

Then it hits the limit and the page life expectancy goes back down massively to <300.

So I'm guessing there is something limiting the amount of memory.

Any ideas on what that would be and how I can fix it?

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Don't need AWE for 4GB of RAM. Simply turn on /3Gb in boot.ini to get a 3-1 split of the address space between user mode-kernel mode. This way SQL Server will get 3GB or VA that can be used for anything, allocations or page pool, which is better than AWE.

However, increasing the engine VA may or may not solve the problem. To get a good understanding of why the DB is slow, use a methodic approach like Wait and Queues methodology.

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