Unknown directory 'appdata_ocjdepk8ube4' (size > 2Gb !) in data directory

Nextcloud version (eg, 20.0.5): 20.0.7
Operating system and version : Debian
Apache or nginx version (eg, Apache 2.4.25): nginx
PHP version (eg, 7.4): 7.3
Yunohost :

I found a big (up to 2GB) unknown directory ‘appdata_ocjdepk8ube4’ in the data directory at same level than users’ directory. Is there a solution to identify where is from ? I would like to remove it.

The 3 users of my instance use only 3,8GB and this unknown directory have a big impact of my backup size :wink:


In my case the biggest sub-directory in appdata_xxxxxxx is preview/ which holds previews/thumbnails of images and files. Perhaps the same for you?

In that directory you can run this command to see disk usage per directory:

du -d1 -h

I am not sure what happens if you remove previews etc.

You’re right appdata_ocjdepk8ube4/preview is the biggest one. and thanks for the command. I didn’t know the parameter -d1

But what 's the purpose of this directory ? 2GB of preview for 3,8GB of user’s data ? I suspect a problem, perhaps an old one, on my instance and I would like to clean (?) it :face_with_raised_eyebrow:

In config/config.php there is a line

   'enable_previews' => true,

If you change it to false you will disable previews (totally, I think), is that ok?
Or perhaps you have enabled pre-generating previews (check with sudo -u www-data crontab -e (replace www-data with user for the web server, this is the defaults on Ubuntu)).
Another options is to reduce the preview sizes, 'preview_max_x', check documentation for valid values.

I agree that the previews take much space, I have it enabled cause I find it much more pleasant when browsing image directories.

Sorry for the delay, I wasn’t connected :slight_smile: and many thancks for your answer.

I will test your different proposals and give a return here

it’s kind of a caching-dir for some nextcloud-“apps.” if you disable/delete the previews they will be regenerated the next time the graphics-files are displayed (eg, someone opens the gallery) and it’s usually faster to use the previews that already exist (in that dir). in one of my installations there is a huge gallery and its previews are ~150GB - so you might want to exclude that from backup.

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I test the 2 options (disabling preview or limiting their size) and both work well.* But only for new files. After deleting directory, I have error msg for all previous files.

Is there any mechanism to force nextcloud to regenerate ? I didn’t find solution in doc.

* If somebody else search the doc, it’s here : Configuration Parameters — Nextcloud latest Administration Manual latest documentation

You’re right, I have to exclude this directory from backup :wink: