suse.de dovecot issues

Hi,

I am one of the people taking over our new suse.de email setup (consisting of dovecot+rspamd+postfix) and wanted to report some issues we experience:

1. we use dovecot-director to distribute users between 2 backend servers that share an NFS mount. We found that it proxies lmtp to a different backend than imap of the same user and that caused NFS stale-filehandle errors on the dovecot-uidlist. It then proceeds to re-generate the dovecot-uidlist with new UIDs that creates trouble for users.

a) shouldn't dovecot use locks (fcntl or flock) to protect such files from concurrent updates?

b) could it generate uidlist in a way that re-generating it, assigns the same UIDs again? E.g. via hash over file content

c) how to get dovecot-director to send all traffic for a user to one backend?

2. We have 2 backends so that we can do maintenance on one of them while users can still access their emails through the other backend. However, we found that stopping dovecot on one backend left users unable to access their mails. Maybe this is related to how user auth works? How to get this HA setup right, so that we don't have a single point of failure?

grep PRETTY /etc/os-release PRETTY_NAME="SUSE Linux Enterprise Server 15 SP3"

rpm -q dovecot23 dovecot23-2.3.15

https://www.zq1.de/~bernhard/temp/dovecot/ has some sysreports.

Ciao Bernhard M.