I've seen in a previous post, that the fact to do an RSYNC might break the  index.. So, I've heard that this is not recommended. that's the reason why I decided to find a way to do a "clean" backup and be able to come back online if needed.

So, do you use an RSYNC and in case of restoring the mailbox, do you do a  simple

 doveadm index -u USERx INBOX

And that's it ? works fine ?

2) I will try the Backup , or Sync.. locally.. Effectively, I don't know where the problem comes from..I have effectively an NFS Mount
 for the mailboxes and a VM for the Email server and that could be another another point of failure :-(

Thanks for sharing.. I am a bit in a rush... I realized that my backup maybe not correct.. and I prefer not to discover it while running into trouble..

I'm not sure what you are attempting to do here. It looks like you just ran a doveadm backup and the process completed for userx with a warning that the remote system (your nfs mount) lost a particular mailbox (possibly your indexes changed or a mailbox was deleted). From the logs you pasted it appears the process completed normally.

I personally do not use dovecot's backup or replication processes. If I needed to I would use its replication process to sync active data between multiple systems, but I have no need for this as of yet. Personally I chose to create offsite backups using rsync a long time ago, as rebuilding a mailbox (reindexing) is very simple.

Try running            doveadm mailbox status -u userx guid '*'    as the mailbox administrator and see if you can find that GUID, 7e05c335174bf1608f0a02004eac7fb4. Also, see if the backup you've written to nfs has the GUID.

On 2/27/22 23:33, Stephane Magnier wrote:

Well no ..I thought that dsync was for synchro " realtime for 2 different places ?

Having no 2 machines in parallel ( Just a single machine ) , I thought that a backup at regular interval  would be enough ?

So, a simple backup should be done by dsync finally ?

Do you recommend finally NOT to do a backup ( Doveadm backup ) but a replication process ? ( https://wiki.dovecot.org/Replication  ) ?

On 2/28/22 06:24, Ben Burk wrote:

Did you try running dsync?

On 2/27/22 23:15, Stephane Magnier wrote:

HI,

Any idea ? Any clue ?

On 2/25/22 21:50, Stephane Magnier wrote:

Hi

I've recently tried to use the Dovecadm backup to backup the emails..  with the following syntax

doveadm -Dv backup -u userx maildir:/mnt/nfs-backup/userx

Sounds to be OK with few emails... Some of them got a lot of emails and one f them got an error and stop !

dsync(userx): Debug: brain S: Import Trash: Import change type=expunge GUID=1725fa475d774ee19cb98dfb6737b4f1 UID=24891 hdr_hash= result=GUIDs match
dsync(userx): Debug: brain S: Import Trash: Import change type=expunge GUID=916ed110b4b1522868be6194f1ae36ff UID=24892 hdr_hash= result=GUIDs match
dsync(userx): Debug: brain S: Import Trash: Import change type=expunge GUID=eb8d75c530a7b02fc26b494d9006c91b UID=24893 hdr_hash= result=GUIDs match
dsync(userx): Debug: brain S: Import Trash: Import change type=expunge GUID=aee9155875c34861fd6500f1f2f51a26 UID=24894 hdr_hash= result=GUIDs match
dsync(userx): Debug: brain S: Import Trash: Last common UID=24894. Delayed expunges=
dsync(userx): Debug: brain S: Import Trash: Saved UIDs:
dsync(userx): Debug: brain S: Import Trash: Finish update: min_next_uid=24895 min_first_recent_uid=24895 min_highest_modseq=35344 min_highest_pvt_modseq=0
dsync(userx): Debug: /mnt/nfs-backup/userx/.Trash/dovecot.index.cache: Compressed, file_seq changed 1645803588 -> 1645803589, size=32, max_uid=24894
dsync(userx): Warning: Mailbox changes caused a desync. You may want to run dsync again: Remote lost mailbox GUID 7e05c335174bf1608f0a02004eac7fb4 (maybe it was just deleted?)
dsync(userx): Debug: auth-master: conn unix:/run/dovecot/auth-userdb: Disconnected: Connection closed (fd=10)

I empty the trash... exactly the same problem...

Any idea why this ??

Thanks and regards,