Dolphin seems to only create thumbnails (~/.cache/thumbnails) of files that are themselves in the cache directory. STEPS TO REPRODUCE 1. Delete ~/.cache/thumbnails 2. Open ~/Pictures/Digi (162 pictures, thumbnails are shown) OBSERVED RESULT No thumbnails are created in ~/.cache/thumbnails, but the "large" and "normal" directories are created, albeit remaining empty. EXPECTED RESULT Thumbnails are created in ~/.cache/thumbnails/{large,normal}/ in the normal fashion. SOFTWARE/OS VERSIONS Linux/KDE Plasma: 21.08.0 KDE Plasma Version: 21.08.0 KDE Frameworks Version: 5.85.0 Qt Version: 5.15.2 (built against 5.15.2) Interesting: When copying the aforementioned Digi directory (holding 162 pictures) into ~/.cache/ and viewing it, the thumbnails in ~/.cache/thumbnails are created. My ~, ~/Pictures, and ~/.cache are all separate btrfs subvolumes on different physical drives, and LUKS volumes.
I did some more testing, since kio was mentioned I used kdebugsettings to set everything to debug logging, and launching "kdeinit5 --no-fork" in a terminal, which resulted in no obvious errors. Afterwards, I persued the filesystem aspect some more: - new user, "/home/test1", "/home/test1/.cache", and "/home/test1/Pictures/Digi" all on the same filesystem -> Thumbnails get written - my user, "/home/c" and "/home/c/.cache" on the same filesystem, but "/home/c/Pictures/Digi" on another filesystem -> No thumbnails get written It seems like thumbnails in ~/.cache/thumbnails only get written when the thumbnailed data is on the same filesystem as the ~/.cache directory.
For me no thumbnails cache files are generated whatsoever, only the folders (large, normal, x-large) are created. > It seems like thumbnails in ~/.cache/thumbnails only get written when the > thumbnailed data is on the same filesystem as the ~/.cache directory. I can confirm that observation. Since my ~/.cache is on a dedicated subvolume there were zero thumbnail files. Testing within ~/.cache do actually save thumbnails as expected. Operating System: EndeavourOS KDE Plasma Version: 5.22.5 KDE Frameworks Version: 5.86.0 Qt Version: 5.15.2(In reply to Christoph from comment #1)
Are you using encryption on the locations / subvolumes in question? > It seems like thumbnails in ~/.cache/thumbnails only get written when the > thumbnailed data is on the same filesystem as the ~/.cache directory. This doesn't explain why I am able to cache thumbnails from remote locations, such as CIFS (SMB) network shares. It might have something to do with the following bug reports, the second one I filed recently to suggest the users be given an "option" to override this default behaviour: https://bugs.kde.org/show_bug.cgi?id=411919 https://bugs.kde.org/show_bug.cgi?id=443806
(In reply to flan_suse from comment #3) > Are you using encryption on the locations / subvolumes in question? > > > It seems like thumbnails in ~/.cache/thumbnails only get written when the > > thumbnailed data is on the same filesystem as the ~/.cache directory. > > This doesn't explain why I am able to cache thumbnails from remote > locations, such as CIFS (SMB) network shares. > > It might have something to do with the following bug reports, the second one > I filed recently to suggest the users be given an "option" to override this > default behaviour: > > https://bugs.kde.org/show_bug.cgi?id=411919 > > https://bugs.kde.org/show_bug.cgi?id=443806 Also to mention, non-encrypted USB drives also have their thumbnails cached: https://bugs.kde.org/show_bug.cgi?id=443806#c2