On 31/08/2025 20:04, Zakaria via dovecot wrote:
Why can't you make HA out of Dovecot CE? Mounting disk using NAS to
multiple servers and take it as a maildir storage, and have dovecot
running in each with a POP loading balancing requests having HAProxy e.g.
in frontend. Also using perhaps MySQL Cluster for virtual users and
connect dovecot to it?
This sounds to me from experience point of view very doable, and not sure
why you think it isnt? No need for syncing data, since NAS will have data
already synced and the bigger it gets the more disks you need to extend
the RAID rack and you can build another server and rack as backup and
write small script to take backup everyday and its sorted?
Zak.
On 2025-08-31 17:30, John Fawcett via dovecot wrote:
> On 31/08/2025 17:02, Gerben Wierda via dovecot wrote:
>> Will doveadm sync in a cron job give me something resembling HA? Don't
>> think so. Replicator does. So, read my question not as 'syncing' is
>> deprecated, but HA-syncing (via replicator) is.
>> As far as I understand it, replicator sends the message immediately to
the
>> other side as it arrives. A, say, once every 15 minutes cron job
running a
>> new doveadm sync doesn't match that.
>> So yes, syncing is not deprecated (I wrote that incorrectly). Doesn't
>> change my situation as replicator is, and I want a true HA solution.
>> G
>>
Hi Zak
I doubt that anyone has something like that working successfully. If
they have, I'd be glad to hear of it. My reasoning is:
1) I would not assume that multiple Dovecot instances accessing and
updating a common mail store is supported unless it is stated somewhere.
My understanding is that you cannot just take a software that expects
to handle a mail store being accessed only by itself and turn it into a
multi instance unless the software supports that feature.
2) In the previous versions of Dovecot there was a specific architecture
supporting multiple servers. Maybe it was there only for managing
scaling, but I am assuming it also managed HA and that without it HA was
not possible.
3) In the new version of Dovecot it has been stated that the features
supporting multiple servers are available in Dovecot Pro and not in
Dovecot CE. I recognize that this statement is not 100% correct since
sync works across multiple servers, however not as HA.
4) I am not familiar with HAProxy, but my doubt about that is whether it
would guarantee to have the same user always handled by the same Dovecot
server, at least as a first approach to not having more than one Dovecot
server accessing the same mailbox simultaneously.
John
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