While I think working from a SD card is not optimal, that’s your choice.
Can darktable write to the SD card at all? That is, if you edit an image, do you get the corresponding XMP file on the card? If you export, does darktable create the output directory, and the output file? Performing those tests would tell us if it’s a general problem writing the card, or if it is related to deleting.
Can you write to the card from other apps? E.g. save a file from Notepad? Can you delete files from Explorer? (Ah OK, I just saw the native filemanager seemingly has this ability in one of your comments above.)
Sorry, I misunderstood the question, I was answering your question about workflow. I haven’t managed my images this way before so there is no comparable workflow for me, Im trying to figure out one that I like and that works for me. The reason Im here trying to figure this out is that Id really like this workflow if I could, technically, get it to work.
We don’t have many windows developers. Most of us use Linux. I think when darktable removes an image, it is sending it to trash. But I don’t think that’s possible in a SD card. It normally just gets deleted.
The workflow you are expecting is not advisable. Any hiccups in the read/write of the FAT formated card and it will corrupt your images. Years ago I was copying images from a vacation to the laptop. Something happen (I think low battery warning) and it corrupted all of the images. I managed to recover most of them, but since then I now swap cards at least mid vacation.
One of the reasons the workflow may not be optimal is that SD cards are not as durable as other forms of storage. Creating the XMP files means writing to the card; deleting images one-by-one means many individual writes – whereas formatting the card (and deleting all images at once) means a lot fewer writes (this is because deleting/formatting does not overwrite the data, only the ‘administrative area’ which stores where each file is on the card, and which areas are free - with a format, you write it once, with individual deletions, several times). The table on this page (though it’s a few years old) indicates at most a few tens of thousand writes for most card types, and much lower than that for some. SD Card Write Cycles Overview - Knowledge Base EN - MOBOTIX Community. At least that is my understanding.
So I proceed with attempting to delete permanently but then I get an error message
For what I can see, darktable simply calls the GTK library (GIO g_file_delete), which has some platform-specific implementation for each OS. Then, darktable simply returns any error message it receives. I’ve done some searches why that call may fail on Windows, but got nothing relevant besides e.g. file system corruption – but that would affect Explorer, too, I guess.
While leaving the images on the SD card may appear easier/simpler/faster, there are a few down-sides.
One is that once you remove the SD card from the reader, and put it back in your camera, you can no longer edit your images with darktable until that card is back in the reader. (darktable needs access to the original image for editing, to read the data…)
Another is that you cannot re-use the SD cards once they are full with your workflow. And they are (a lot) more expensive than hard drives (disks or SSD) per TB.
Now, the cost argument will play differently for everyone. But the “not able to edit” would be a deal-breaker for me: I can get at best 600 images/card (I could use bigger cards, true), and I currently have a collection of ~30 000 images, after culling… That’s 50 cards… Again, I could use bigger cards, but that would still leave me with a nice stack of cards to handle…
Now imagine I want to recover a selection of images spanning several cards, for export to generate e.g. web pages. I’d keep changing cards… Anyone here old enough to remember floppy disks?
And how do you handle backups in that SD workflow? While SD cards are sturdy, they are not indestructible. So you’ll have to do a full download at least once, anyway (later backups from hard disk can be done in background or at night, for TB at a time)
I teach photography and over the years I have seen on a number of occasions when my students have deleted images from their SD cards using a computer like you are trying has caused the card to become unreadable by the camera. Luckily, I have been able to reinstate all these cards by then formatting the card in the person’s own camera. What you are trying to do is prone to problems and I can not recommend it.
What I do with my images is copy and import all my images to my computer. I then can sort out the ones to keep or delete on the computer. I would not attempt this for the SD card.
When I am travelling I take my laptop and each day import and copy the days new images to my computer. DT can tell which images are already copied and which are new, so I don’t end up duplicating images. I then leave the original file on the SD card as a backup in case the laptop is stolen or something else happens to those images.