On Workstation 5.5 (Linux host OS), I could set how much of the guest VMs were allowed to swap.
I have two primary development VMs, each with 512MB RAM. For performance reasons, I told Workstation to keep all VMs resident in memory.
With 2GB RAM I could fire up both dev VMs as well as a Subversion server (Linux guest, 128MB RAM).
Now I'm primarily running Fusion. (Yes, I know it's beta, but VMware's betas have always been amazingly solid. I do back up often.)
I'm finding that with a 2GB RAM 17" MacBook Pro that I can run one dev VM fine, but if I fire up the second the whole machine slows to a crawl. The external Firewire HD that houses the VMs is trashing something nasty. I can't tell whether the internal hard drive is thrashing, but the swap file proliferate.
I'm assuming that Fusion defaults to allowing part or most of the guest VMs to swap out. Is that what's going on? If so, is there a config file tweak that will keep VMs resident in available RAM?
I don't run too many VMs often, but I was just hit with this again when I wanted to copy data from one dev VM to another.