[Exim] RAM in mail server

My hard drive on my mail server is doing alot of access (slow seek time,
etc). I have 10,000 users on the 400Mhz Pentium II with 128MB ram. I am
wondering if my access is being slowed down by mail transfer, or from
swapping. how do I tell which?

I am running bsdi 4.01

Sincerely,

Richard G. Duvall