[Dovecot] Adding capacity by simply migrating to dovecot -- thank you

[Benjamin Connelly]

We run a mail service with some hundreds of domains and thousands of  
users. Xeon 2 CPU server hosting the imap, pop, webmail, db and all  
trimmings (sepparate servers scanning for spam/viri)

The server was io saturated and performing poorly, especially for  
large webmail users. A constant queue of hundreds of ops per second  
were taking too many miliseconds each (gstat.) Load average often  
spiked over 15! We planned to add a second backend imap/pop machine  
but first migrated to dovecot (from courier.)

Like a miracle, the load average stays below 1 now, nor do the disks  
saturate! All's well and webmail performs snappily even during peak  
usage!

Granted we also upgraded freebsd which supposedly has made leaps to  
better schedule tasks across multiple processors, but this is not a  
many core machine - just 2.

We almost don't need to scale up our architecture, tho will, thanks so  
very much for this wonderful software Timo!