I have a problem with an Android phone, which is deleting files that I put on an SD card with my laptop. The card is brand new, and when it arrived it was formatted exFAT. I left the filesystem alone, since I knew it was destined to go into the phone. I transferred hundreds of files to the card with my laptop (SparkyLinux, based on Debian 12). After inserting the card into the phone about a third of the files were missing. I muttered invectives toward Samung (vendor of the card) and to the designers of the exFAT filesystem, but nothing helped.
Eventually I pulled the cad out of the phone and mounted it back in the laptop. Sure enough, something on the phone had deleted hundreds of files. As to how or why I have no clues. Android is supposed to be able to read the ext4 filesystem, so I reformatted the card to ext4, then rewrote all the files. It's now ready to go back into the phone, but before I do that I want to make everything read-only, up to and including maybe the entire drive. My knowledge of Linux is not great, and my Android abilities are much less. I have no illusions that Google & Co. may have ways to defeat my efforts, but I still want to give it my best shot. I could use some instructions and suggestions for how to solve this problem. :)
