Fairly new with nextcloud but preview folder has huge size

RustyFatDog · November 18, 2019, 12:34pm

Ive been recently given a nextcloud where I work and ive been having a few problems regarding disk usage.

Seems like theres a Preview folder that uses up all the space on the hard drive.

Can i just delete everything inside that folder or is there a procedure i have to do?

I have 0 idea how the file system works for it.

Thanks!

j-ed · November 18, 2019, 1:28pm

I think a good point to start is the adminstrator guide in which the preview function is explained. If you want to customize the preview generation please have a look on the Preview Generator app.

Deleting the content of the preview folder is only a short term solution unless you’re

disabling the preview generation in total
or
customize the configuration of the preview generation so that it fits your needs
or
make sure that enough disk space is available on your hard disk.

gas85 · November 18, 2019, 2:09pm

Hey, check this out regarding config this:
https://ownyourbits.com/2019/06/29/understanding-and-improving-nextcloud-previews/

and this

And remember, after you change the config, you have to regenerate previews again. Here is a good explanation how:

github.com/nextcloud/previewgenerator

How to config? How to reclaim space?

opened 07:07AM - 04 Jan 18 UTC

tavinus

Hi! #### Say I apply these settings ```sh sudo -u www-data php /var/www/nex…tcloud/occ config:app:set --value="64 128" previewgenerator squareSizes sudo -u www-data php /var/www/nextcloud/occ config:app:set --value="64 128" previewgenerator widthSizes sudo -u www-data php /var/www/nextcloud/occ config:app:set --value="64 128" previewgenerator heightSizes ``` #### And my `config.php` has ```php 'preview_max_x' => 2048, 'preview_max_y' => 2048, 'preview_max_scale_factor' => 2, ``` OR ```php 'preview_max_x' => null, 'preview_max_y' => null, 'preview_max_scale_factor' => 2, ``` #### And then I run `generate-all` Would the generator set the `'_max'` file to 128 pixels only and then just use that size as maximum even when I click to open an image? Or is just for pre-generating and nothing else and then the bigger image will be generated when clicked? I am but confused because I got some mixed results here, but I am guessing the browser cache was doing its thing. What would be the recommended settings for a big install with lots of images? We want to be able to browse it fast and have the best full-screen experience, but we would like to avoid having 30+Gb (still processing) of preview images data (which also goes to the backup, btw). And then there is also the question if it is safe to remove the preview files and/or folders to reclaim that space, which I already asked on core. https://github.com/nextcloud/server/issues/5263#issuecomment-355202378 I would probably prefer to make some simple bash scripting to remove just some bigger sized PNGs so I don't have to reprocess everything. That is easy if there is no problem with the database and other stuff. In any case, because I was testing different configs as well, I can see many different preview images above 1024px for some files, which is probably the reason for such a big footprint. I would prefer to have just the smaller sizes pre-generated (for menus and icons) and let the big stuff be done as needed. Can this be done with the config above? #### Edit Also, what does `pre-generate` really do? It runs in 1s and does not seem to create any files here. `generate-all` scans everything (for days) and sucks the processor and creates the pngs, but `pre-generate` does not seem to do anything.

RustyFatDog · November 18, 2019, 2:17pm

Well as a temporary solution. Can i just delete whats inside the preview folder? Or can i like break something if i do?

gas85 · November 18, 2019, 3:11pm

It will not be “brocken”, but simply delete preview folder will not delete links in database, so that new preview will not be generated.

To “reset” the preview cache

Stop Webserver (apache / nginx)
Moved the appdata_instaceName/preview folder outside the appdata folder. You can just remove it if you are confident.
Run sudo -u www-data /usr/bin/php /var/www/nextcloud/occ files:scan-app-data to fix database
Start Webserver and Test everything works
Finish up (delete moved folder, etc).

RustyFatDog · November 19, 2019, 7:47am

We dont really use the webpage function of nextcloud, we just sync it with the computers. But ill give what you said a try!

gas85 · November 19, 2019, 8:36am

Then you could disable previews in config.php afterwards:

'enable_previews' => false,

RustyFatDog · November 28, 2019, 7:08am

Do i have to add this line or should it show up? Cause it doesnt for me.

gas85 · November 28, 2019, 10:44am

You have to edit your config.php (usually under /var/www/nextcloud/config/config.php), if you have this parameter already there, change it to false, if not you have to added it, because default value is true or previews enabled.

After you edit your config you have to do some DB cleanup as described above.

kim62537 · September 21, 2021, 6:04pm

@gas85
Thanks for the solution

But how can i do the rescan WITHOUT occ access (no bash or ssh) on a shared hosted system ?
That is a very big problem with nextcloud (also running the index updates is not possible).

i disabled previewing in the config (months ago), but the folder contains still 12 GB (GIGAbyte !!!) files. why isn’t nextcloud automatically (and f.eg. successive) rescanning and cleaning those files ? can those files & folders within “/cloud/data/appdata_xyz12345678/preview” simply be deleted without loosing data ?

gas85 · September 22, 2021, 8:23am

Check Web OCC App: OCC Web - Apps - App Store - Nextcloud But this is not working with NC 19+

It is not cleaned automatically, you have to reclaim space:

kim62537 · September 22, 2021, 4:31pm

Check Web OCC App

As you already noted: Not available for V19+ (and i am using V20 currently)

It is not cleaned automatically, you have to reclaim space

Yes. I recognized. But that would be an interesting question for the nc developers, WHY those settings are not checked by interval or cannot be triggered manually from the normal admin/user backend.

Run sudo -u www-data /usr/bin/php /var/www/nextcloud/occ files:scan-app-data to fix database

Simply not possible, because there is still no SSH or bash access.

That is simply bad developed, when space is filled up automatically - but for cleaning it you need manual action and special privileges. 12 GB is a lot of space for useless data … i think i have to replace nextcloud by another software.

gas85 · September 22, 2021, 5:11pm

I would not blame nextcloud. If you will delete all pictures, previews will be also deleted, it is only some issue with defaults.
Try to install webmin, this allows you to have ssh even in web.

bb77 · September 23, 2021, 9:33am

In addition to what already have been said, you could also limit the size of the previews, which should safe you a a significant amount of space.

https://docs.nextcloud.com/server/latest/admin_manual/configuration_files/previews_configuration.html