Hello everyone, I am currently running Dovecot as a high performance solution to a particular kind of problem. My userbase is small, but it murders email servers. The volume is moderate, but message retention requirements are stringent, to put it nicely.
Many users receive a high volume of email traffic, but want to keep every message, and *search* them. This produces mail accounts up to 14+GiB. After seeing the failures of my predecessors, I transitioned to Postfix/Dovecot and haven't looked back. Things are running nicely with the below 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 15k RPM SAS drives on RAID-10 via direct attached Dell MD-1000.
We are transitioning other services to high availability, and I'm wondering exactly how to provide some kind of near-realtime failover for my Postfix/Dovecot machine. The MD-1000 provides nothing in the way of iSCSI, but it *does* have two SAS connections available, only one of which is in use.
I have been looking at the Dell EqualLogic stuff and it seems to provide what we need. I can get most of the information I need from the rep, but I wonder if anyone has any experience with high performance requirements on these kinds of storage.
I'd like to continue running my current hardware as the primary mail server, but provide some kind of failover using the SAN. The primary usage of the SAN will be to make our 2TB document store highly available. I'm wondering what kind of options I might have in the way of piggybacking some email failover on this kind of hardware without sacrificing the performance I'm currently enjoying.
Is it possible to go with a virtual machine mounted on iSCSI acting as a backup mail server? How would I sync the two, NBD+MD? Any experience doing this with maildirs? I wonder about the performance.
Can it be as simple as attaching my MD-1000's second controller to the SAN magic box via SAS and pressing the Easy button?
Is it as expensive as running my primary mailserver mounted from the SAN via Fiber Channel? Will that get me under 30ms latency?
I welcome any suggestions the group may have.
-- Wayne Thursby System Administrator Physicians Group, LLC