On 10/12/2013 09:54 AM, teknet9 wrote:
Hello Everybody,
I need to migrate my old postfix server to a new machine.
Domain will be the same. I would like to make this migration seamless
for the end users and give them 1-2 months for migration (both servers
should work at that time correctly).
1 to 2 *months* ? why ?
<snipped hugely convoluted migration path>
Here's what I propose:
- install postfix on the new server, and configure it identically to the
existing server, except the following:
* relay the domain in question to the old server, by removing it from
mydestination and moving it to relay_domains.
* Use your existing userdb to verify valid recipients with
relay_recipient_maps.
* set the old server as its /specific/ relayhost using
[oldserver.example.com]
- switch MX to point to this new server; all incoming mail will enter
via the new server and be delivered to the old one.
* Now wait long enough for the old MX to expire from any caches
worldwide; this is the longest part of the migration, since it's not
under your control. Be patient, and plan well in advance (say a week.)
- install your mailbox server (dovecot is preferred) and plan your
downtime.
* Make an initial copy of your mailstores to the new server so you won't
have to copy so much when you're actually migrating.
- during your downtime window, stop postfix and dovecot, and rsync the
mailstores to catch up
* also change the new server's postfix configuration back to what it
should be (i.e. no more relaying)
- switch the hostname(s) for the users to the new server, or stop the
old one and switch its IP (this is faster)
Whether you use a new IP or switch the old one with the new server is up
to you (the latter avoids DNS downtime.)
Also consider now implementing separate DNS for smtp in, smtp out, and
imap access.
This avoids DNS-related issues when you decide to split these functions
up later.
--
J.
