On Jul 14, 2014, at 1:22 PM, Anders Wegge Keller <we...@wegge.dk> wrote:

> 
> A frind of mine and I are running a dedicated server, that among
> other things host mail for ourselves and friends and families. All in
> all about 15 different domains with 35-40 users. The machine in
> question is old, so we are doing a slow transition from the old server
> to the new one. So far, we've managed to move web hosts
> seamlessly. Due to the technical capabilities at some of the user
> base, it would be nice to get to a setup, where we can move individual
> users imaps from the old server to the new one, as we get the time to
> visit them.
> 
> I have an idea how such a transition could go:
> 
> 1. Upgrade the old dovecot 1.2.15 to 2.1.whateveritis from debian
>    squeeze backports.
> 
> 2. Set dsync up to replicate mails from the old server to the new
>    server. I know that 2.2 is recommended, but with a limited amount
>    of user, I'm willing to take a performance hit.
> 
> 3. Migrate my parents &c to use the new server.
> 
> 4. When all users have been moved on to using the new server, upgrade
>    MX records for the domain to point at the new server.
> 
> 5. When all MX records are updated, decalre success.
> 
> 
> Is this feasible, and what would the risks be. For instance, during
> step 4, mails are bound to arrive at bothe the old and new server for
> some time. Will this cause problems?
> 
> Is there a simpler solution to the problem?
> 
> -- 
> /Wegge
> 
> Leder efter redundant peering af dk.*,linux.debian.*

I did this several years ago using imapsync to sync the accounts from an old 
server to a new server. Once all the accounts have been sync'd and you're ready 
to cut over to the new server, run imapsync one last time to catch anything new 
that's arrived. It will go very quickly. Disable postfix/dovecot on the old 
server and change your DNS to point to the new server. Or better yet, if the 
old and new servers are on the same network, just swap the names and IPs of the 
new and old servers.

-Terry

Terry Barnum
digital OutPost
http://www.dop.com

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