On Oct 12, 2013, at 17:04, teknet9 <tekn...@o2.pl> wrote: > Thank you for advise. > I have many users i can not allow for any downtime (not even few seconds). > Also i can not loose any single email. > Your solution will not guarantee that. > > I am looking for true HA solution. > > That is why both servers needs to work at the same time for 1-2 months > to allow users to test new account and to migrate when ready. > During migration both servers needs to work correctly (two way sync)
Don't run them side by side, but cut over. This is much less of a disruption for your users than having them test their account and whatnot. Testing is your job, not theirs. Follow the suggestions already given. Whether Jeroen's suggestion or a straight cut-over with hot sync followed by a cold sync will work best for you will depend on the specifics of your setup. If you prep this properly you can probably do this within a planned downtime window of half an hour, maybe even less. Mvg, Joni -- >>> 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. >> >
