@mfabry does your system recognise your sd card? I don't do linux but in Windows it is my computer
@cava
I have had similiar problems with my SD card.
Calibre would only write 173 directories to SD card no matter how I formatted it *FAT, Fat32, NTSF).
Windows would give me the same error on Fat at least though so probably an OS thing.
Calibre puts all the files/folders on the root on the SD card although it uses the Sony convention on the internal memory.
Calibre doesn't delete empty subfolders when you delete the last book from the collection via the reader, which could be normal but I expected it to with it hooked up and automatic management turned on as I can resend a book and then delete it via USB and the collection folder is removed.
My solution was to copy all of the books and send them via Sony Reader software which I haven't used much. Then they went to the correct place instead of the root.
Calibre recognized that all of the books were on the device and wrote its own files.
Took Sony 3+ hours to finish whatever it does after I ejected it and disconnected it. Battery almost gone. Plugged it in again and charged. Took less than an hour to come back to life
Today I got brave and put another 1000 books on to see waht would happen.
Collection folders all went to the root, but there was only 114 so so far so so good. Ejected and disconnected and took less than 1/2 hour to be ready with no noticeable battery drain.
I cannot see that calibre could be at fault in the long sony boot time.
Would be nice if the books and folders did not all go to the root though.