Posted by Erland Sommarskog on 03/18/06 01:13

dries (dries@bessels.stop-spam.org) writes:
> From a previous sys-admin I inherited a a MS-SQL (2000) machine with 3
> instances. It is a nice machine with 4 Gb of memory but the memory
> allocation is very weird:
> Instance A: 1400Mb
> Instance B: 1000Mb
> Instance C: 80Mb (!)
>
> Instance C is performing badly under a bit of pressure which seems not
> strange considering these allocations.
>
> With that in mind, is there a way to check and re-allocate memory? I'd
> like to see if the instances really need these amounts of memory and if
> not, to move some over to other instances.

You cannot reallocate memory between instances per se, but you configure
per server the max amount of memory an instance can use.

SQL Server's general strategy on memory is to grab as much it needs
and that is available. The use for this memory is cache. The more data
that is in cache, the faster data can be accessed. When there is competition
for memory, SQL Server will yield. In this it appears that the three
instances are competing.

3 instance on 4GB may be a tad low. You are running with the /3GB switch
in window?


--
Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se

Books Online for SQL Server 2005 at
http://www.microsoft.com/technet/prodtechnol/sql/2005/downloads/books.mspx
Books Online for SQL Server 2000 at
http://www.microsoft.com/sql/prodinfo/previousversions/books.mspx

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