Wayne Thursby put forth on 2/15/2010 10:24 AM:

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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.

The same ESXi/RAID combo are also running several other VMs using 7 of its 8GB of RAM.

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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.

Sorry if it's less impressive, but I've certainly configured the VM for 4 cores. The cores are shared equally between all VMs, I've done no prioritization because I've not had any performance issues related to resource contention.

Having 10x15k RPM spindles to seek across, and 512MB of cache on the controller, means I can give Postfix/Amavis/Dovecot 3GB of RAM to use, and 1GB of it is always used for cache, without ever dipping into swap. I get occasional spikes to 30ms of disk latency, but it stays below 5ms for most of the workday.

Also, are you seeing the classic system clock drift of ESX guests, and if so, is it causing problems with smtp and imap?

Not at all, that's what the VMware tools are for. The ESXi host is configured to use our NTP server inside the VPN, and the VMware tools package synchronizes the guest clock with the host. I ran into this on our webmail client as well, then I discovered how easy it really is to install the VMware tools on Ubuntu, so it's no longer a problem.

Don't want to stray off topic, so I'll start a new thread, but I'm now attempting to bring High Availability to the mix, and could use some suggestions.

-- Wayne Thursby System Administrator Physicians Group, LLC