Sync between two servers

villegg

Hi, I’ve seen some threads about this but haven’t really been able to understand them.

I currently have one mailcow server in the cloud but I’ll deploy one on-prem when my ISP get PTR-records setup etc…
I would like to have the inboxes in these synced. How should I start/proceed? Should I use the sync function or is there a better alternetive? It will be run as a “hot spare”, it will always be active but it will have a higher priority in the mx records.

Thanks for any help.

esackbauer

https://docs.mailcow.email/backup_restore/b_n_r-coldstandby/
You could use this. I don’t see why you would have 2 MX records, it makes life only complicated, because
here is no real cluster or failover fucntion in mailcow.
In case the primary mailcow breaks down, just change the mailcow hostname IP address (A record) to the IP of the secondary which you have backed up regularily (like every day or every couple of hours) with the coldstandby script.

villegg

esackbauer Well I’d like not to change the dns records, I’d want it to “failover” to the second node automatically, the one with a higher priority so I don’t lose any incoming emails and then start reciving/sending from the lower prio when it’s online again. It seems like what you are suggesting would cause downtime?

esackbauer

villegg

You won’t lose any mails, when the primary mailcow is down, the sending mail server will retry for at least 48 hours.
As I said, there is no possibility to automate failover, mailcow is not build with clustering.
Theoretically you could automate the change to the DNS A record, like with monitoring which can noticing downtime and will change the DNS record via script to the secondary. But I wouldnt want this as monitoring can have false alerts and then you get into trouble syncing your mailcow back and forth. I do this manually.

If you do this for business critical mails, you should consult the guys at servercow.de they have more likely experience.