Wayne Thursby put forth on 2/15/2010 10:24 AM:
My Setup: Postfix and Dovecot running on the same virtual machine on a Dell 2950 with 1x Xeon E5440 on ESXi 4. Maildirs served up by 10x146GB SCSI drives on RAID-10 via direct attached Dell MD-1000.
Interesting setup Wayne.
Serving 600+ users, mailbox sizes up to 14GiB with constant heavy searching (no fts yet) and filtering (sieve and IMAP clients). 80,000 messages delivered per week, 95,000 messages rejected, 17,000 spam. 15 minute Load average stays under .50 all day with 4 CPU cores.
How many CPUs are listed in /proc/cpuinfo under that Ubuntu VM? ESX by default only exposes one CPU(core) to a VM guest OS. Any chance you didn't tweak the VM config and that your Ubuntu guest is only running on time slices of a single core? Your results are even more impressive if that's the case.
Also, are you seeing the classic system clock drift of ESX guests, and if so, is it causing problems with smtp and imap?
-- Stan