I've recently added 2 GB of RAM to a couple of the mail servers in CSAIL, doubling their memory to 4GB. This is in part due to SpamAssassin 3, along with the rulesemporium.com rulesets, using significantly more RAM than previous versions. The volume of incoming mail (both spam and ham) has also grown since we first deployed these servers. Thus far the improvement in throughput on the spamassassin system is noticable.

This re-emphasizes the need for better trend monitoring on these systems, though. I want to be able to point to a change in a graph and say "This is because we added more RAM to these servers." We need to come up with a good strategy for tracking the workload on these machines over time and presenting it in a meaningful way. This will be interesting for a number of reasons, and I'm disappointed that we haven't been keeping good historical performance data all along.