>
> Are there any current, free high availability strategies for Dovecot ?
I would say the major issue with high availability is having your data readily
available and updated across your nodes. To solve this I would go full object
storage with this ceph integration for dovecot.
Ceph is really high availability storage solution, no doubt. The plugin consist
of storing your email as objects and communicates directly with ceph via rados.
So your mail server nodes are around 8GB while the TB's are stored in ceph
storage.
The only thing you need to do is use this dovecot director or some other
solution to bind users to a specific mail node.
However, next to the storing of emails in object storage you have the indexes,
currently this is solved by storing these on cephfs. I had some issues with
cephfs that is why I am rethinking what to do. Maybe I will put indexes on rbd
images and sync those somehow between nodes.
I also noticed some write amplification on my setup, I can't remember
exactly but I think in my case I had twice the storage being used, I need to
retest this though. So with the default 3x replication in ceph, I think I came
near 6x times...
https://github.com/ceph-dovecot/dovecot-ceph-plugin