[Dovecot] 1.0.15 -> 2.x upgrade for mass hosting environment

[Ed W]

On 01/03/2011 13:24, lists at truthisfreedom.org.uk wrote:
> Hi all,
>
> We're looking at upgrading our current mail platform from 1.0.15 to 
> 2.x to take advantage of the new director functionality.
>
> Our main concern is the number of mailboxes involved (circa. 300K) and 
> the rebuilding of the index files, especially as it seems that once 
> you've upgraded, rolling back requires the deletion and recreation of 
> all indices.
>
> Has anyone worked on an upgrade like this in the past? If so, do you 
> have any war stories you can share either on or off list?

Hi, don't have an installation of anything approaching your size.  
However, I do regularly see folks missing out on the idea that its 
reasonably straightforward to have both Dovecot (old) and Dovecot (new) 
versions running at the same time and migrate users over slowly rather 
than in a big bang?

Personally my own experience was that changing from v1 to v2 was a 
fairly unexciting upgrade (as the admin) other than the obvious (large) 
change in configuration required.

Oh, one feature of Dovecot 2 which isn't on by default, but I have found 
very interesting is the "COMPRESS" IMAP feature.  You need to enable a 
few config changes, but after that many clients can talk over a gzip'd 
tunnel, which in my testing leads to a decent reduction in bandwidth.  
It's especially nice for mobile use (eg Profimail on Nokia S60)

Good luck

Ed W