SD Cards "forgets" written data I have an SD Card I bought from ebay. It works, sort of.
Recently, it somehow acquired the weird habit of "forgetting" things I copy to it.
For example;


I would normally place my music folder to the left taking half of the screen, and the window with the sd card to the right taking the rest of screen.
I would then copy a folder to the sd card
safely remove the sd card (or not, tried it both ways)
Pull it out
Place it into my phone (or back into the mac)
Can't find the copied folder, like I've never copied it.


This is weird, and only happens sometimes. I think it happens more when I pull out the card up to 5 minutes after I copied something.

Is this a cache problem? What's the course of action to find the root of this?
It sounds like that SD card has a faulty controller chip. From your description, I'm guessing that you bought it second-hand through ebay, so you might have been "burned" there.

Something you can try is to open Disk Utility, choose the SD card, and then click Verify Disk.

Something else you can try (crossing fingers) is to reformat the SD card and hope for the best. However, if the SD card is acting flakey, then it might be best to scrap it for a new one.

Question: In Disk Utility, select the SD card and choose Info. What File System is the card formatted for?