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On 09/07/2026 13:30 EEST MK <dovecot-ml@mk.de> wrote:

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On 09/07/2026 11:58 EEST MK via dovecot <dovecot@dovecot.org>> wrote:

Hi everyone,

I have a two-server setup where all user data from the actively used server is periodically transferred to the second server using "doveadm >backup". For this, I currently use a script that caches a list of all users (containing only the usernames) via "doveadm user '*' " and then >executes the command "doveadm backup -u [username] tcp:1.2.3.4" (target host) for each user. I use a similarly structured script for a daily >"doveadm purge", where a purge is performed per user instead of a backup.

Under version 2.3, I always ran both commands using the "-A" flag (doveadm purge -A and doveadm backup -A tcp:1.2.3.4). Since migrating >from Dovecot 2.3 to 2.4, this no longer works. When running the purge, the process always aborts after a certain number of users with the >following error message:

doveadm(john@doe.de): Error: auth-master: userdb list: User listing returned failure

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Try adding

log_debug=category=auth

and see if it can shed light one this.

I'll add it to the config and get back next time the problem occurs.

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It's not the same User allways but after nearly the same time or amount of users the script has processed. Since I couldn't identify the exact cause of the error and suspect it might be related to changes in how the SQL iterate query is >integrated in the 2.4 configuration (I use MySQL as the backend) I switched to the script described above.

Then since is used the new script I have a non-reproducible issue. After the initial data transfer (when the target is still empty) the >amount of data is equal to the source. Then after one of the next transfers the data is twice as high. It is random as to which subsequent >transfer triggers this. When comparing the quotas on the source and target server, the output is identical on both. Even running quota recalc >makes no difference. If I check the user directories, I can see that the storage folder contains nearly double the number of files and used >disk space per user.

My second problem is that when I run the purge script on the second server (target), it sometimes deletes all emails for all users, also >non-reproducible. Afterwards, all files under "storage" are gone, and the quota shows 0 emails. I did not have this issue with the exactly same >purge script on the first server which is the source for the backup.

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What does your purge script do?

I have attached it so you can take a look. Is it a known issue that the -A option doesn't work as well as it did in 2.3?

And you are sure it's the purge doing it, and not running doveadm sync?

If you mean delete everything, yes. There is nothing else running there. No other scripts, nothing other is accessing Dovecot. A few times I have seen it live and the other times I can see in my logging that when the script starts the space is sinking and sinking near to >zero until the script ends. I'm logging the disk space every minute.

It’s clear that these are two different problems right? (purge deletes everything and backup writes to mutch data)

What do I have to search for in the logfiles if the problem oncours? What is interesting for you? The debug makes realy mutch log entries.

Update to this. Since I activated the debugging on 09/07/2026 the problem did not occur again, really strange. I can't explain it sice I haven't changed anything other than enabling debugging.

Oliver