[Dovecot] Best way to migrate versions and machines

[Rick Romero]

Quoting Ed W <lists at wildgooses.com>:

> On 17/02/2011 15:29, Donny Brooks wrote:
>> We are looking to migrate from our current mail server running  
>> dovecot-1.2.11-3 to a new mail server running the latest dovecot  
>> (2.0.9?). So this would not only be a version change but also a  
>> machine change. We currently use Maildir for storing mail and would  
>> like to stay that way.
>>
>> Has anyone preformed such a feat and it worked? Looking for any input.
>>
>

I've done it two ways - Rsync and ZFS snapshots.  Both methods are  
pretty much the same.
I have multiple satellites doing SMTP incoming/outgoing and dovecot on  
a primary 'file server' with NFS exports.
1. replicate all data
2. replicate diff data  (do this until the update window is small)
3. disable deliveries (for me, disable qmail-send, umount NFS mounts)
4. replicate diff data
5. turn off IMAP/POP
6. replicate diff data
7. Migrate IP address/Change FW rules/etc
8. Turn on IMAP/POP
9. Turn on deliveries

For my last ZFS migration I only had 2 minutes of 'downtime' from the  
user's perspective (Step 5 -> Step 8), as the necessary changes were  
already staged.

Rick