We have a newer Two socket server with Quad Core processors. On this server we are running two instances of Sql 2000 SE SP4 and the Server OS is Windows 2003 Enterprise with service pack 1. The server has 8GB of ram. The question is should we set each instance of SQL to run on seperate processers under Processor Control. Currently each instance is set to use all available processors and the minimum query plan threshold is set for 5. Would there be any performence gains if we divided the processors between the two Sql instances?
More than dividing the processors, you should (1) Upgrade your SQL Server to SQL 2005 SP3, (2) cap RAM to each of the SQL servers to a max limit so one doesnt eat up all the RAM and starve the other. SQL 2005 responds to memory pressure much better than SQL 2000. Also, you should upgrade your OS to SP2. Having done these, you should measure performance numbers for each of the instances, and if you see CPU pegged around 90% then you could consider setting MAXDOP..
Welcome to the forums. On what Dinaker referred is correct in order to get maximum operability system resource SQL 2005 is better than 2000 due to DB engine changes between the versions. But at this moment I would like to ask you what kind of performance issues you are facing with existing platform?