[Dovecot] Significant performance problems

[Brad Davidson]

Chris,

> -----Original Message-----
> Subject: Re: [Dovecot] Significant performance problems
> 
> Try bumping up the RAM on both servers to 8+GB, and make sure that you
> don't have any mount options that would prevent the client from
caching
> data - noac for example is a killer. You could also try mounting with
> noac, and disabling or turning down speculative readahead on the NFS
> server.

Sorry - don't try noac, try noatime! Big difference!

As an additional data point, I will say that we see Dovecot processes
for 900 concurrent users consume about 3GB of memory. If your system is
anything like ours, you've probably got less than 1GB of memory left for
the kernel to use as filesystem cache. Throw as much memory as you can
spare at the Dovecot and NFS servers, and see what happens.

-Brad