Nextcloud backups

I have nextcloud intalled in a docker (Nextcloud Hub 3 (25.0.5)).
I have been setting up scheduled backups using the backup app. I have set a “external storage” in a local folder /backup and I have set Restoring point location to External storage local::/backup/ and Restoring point location to NextCloudBackups, then I set App Data to local::/backup/ and folder AppData. Neither of this folders (NextCloudBackups and AppData) exist yet on /backup. I have set that the backup should be compressed but not encrypted, and that the backup will be done from 1:00 to 4:00, allowed during week days and 24 days interval between full backups and 3 days interval between partial backups. Retention policy is set to 3 for local app data and 5 for external storages (default).

The backup process is detailed here. As far as I understand when I launch a backup a temporary backup should be created in AppData, then compressed and moved to NextcloudBackups, correct?.

Mi /srv/www/htdocs/nextcloud/data is 94GB size.

So, once set I launch a full backup. Right away the directory AppData is created by the system and begin to create files there … OK. The directory NextCloudBackups still does not exist. The server is put in maintenance mode.

This first step last less than an hour and the server goes out of maintenance mode. In the web the full backup appear as OK, but still not packed nor zipped.

/backup/AppData directory is now 68GB.
/backup/NextcloudBackups has been created by the system now, but is 4K in size.

First thing I don’t understand. I thought the backup to AppData is done without compression so it should be greater in size than my full nextcloud, so it should be greater than 94GB and not 68GB.

I let it work … next day in the web interface the full backup appear as packed and zipped

/backup/AppData directory is now 83GB.
/backup/NextcloudBackups still is 4K

So it has grown in size but is still smaller than mi nextcloud size … well if is zipped it makes sense.

aldebaran:/backup # du -sh * 
83G     AppData 
4.0K    NextcloudBackups 
53M     nextcloudSQLbackup20230513.bak 
aldebaran:/backup #

two days latter a differential backup has been done, that’s fine, 3 days total since full backup so is on schedule. But.

aldebaran:/backup # du -sh AppData/* 
110G    AppData/20240529061505-full-ccrt5BfspKpXqBd 
1.6G    AppData/20240601071003-differential-7JwgJYZUuDyCsqQ 
aldebaran:/backup #

The full backup has grown again. Why?

And more: NetcloudBackups seems to be still unused.

10 days later I check the process. I have two new differencial backups in AppData … thats OK each 3 days a new differential backup

aldebaran:/backup # du -sh AppData/* 
124G    AppData/20240529061505-full-ccrt5BfspKpXqBd 
457M    AppData/20240601071003-differential-7JwgJYZUuDyCsqQ 
2.0G    AppData/20240604071003-differential-tPfcMS9iHPSAOWf 
458M    AppData/20240607095004-differential-Vp2KRhyydnKN5Cn

but the full backup has grown again!!!

And now I see for the first time that the NextCloudBackups directory is not void.

aldebaran:/backup # du -sh NextcloudBackups/* 
57G     NextcloudBackups/20240529061505-full-ccrt5BfspKpXqBd 
452M    NextcloudBackups/20240601071003-differential-7JwgJYZUuDyCsqQ 
452M    NextcloudBackups/20240604071003-differential-tPfcMS9iHPSAOWf 
452M    NextcloudBackups/20240607095004-differential-Vp2KRhyydnKN5Cn 

is 57GB size, smaller than mi nextcloud, smaller than the one stored in AppData…

Why?

The answer that comes to my mind is that the full backup is still in process: it has been created in AppData, growing to 124GB, then it is been moved to NextcloudBackups … but 10 days?