64B Ultra card seems to be read-only

Memory Cards SD | microSD | CFast | CFexpress | CompactFlash
1

I have a 64GB Ultra MicroSD card which has been working fine in my phone for a year or so.

Recently the phone has been acting a little strange, and I’ve tracked it down the the MicroSD card - it seems to be unable to hold on to anything I write to it.

I can save a file to the card, and read the file perfectly well while the card is still mounted. If I unmount the card and remount it, the file is gone. The same with deletions, and even formatting. I can do a full NTFS format (not a quick format) and the card appears blank, and I can save new data to it, and read it. If unmount the card though, it’s back to the state before the format - I can read all the files on it too.

The only thing I can think of is that the file allocation system is corrupted somehow.

Really strange. Have I just managed to get the card into a read-only format, or is it broken?

Also, I’m not using an SD-card adapter. I have it in my phone and have the phone connected via USB in data-transfer mode.

2

And yes, I meant ‘read only’ in the title… :flushed:

3

Most memory cards come formatted as FAT32. The newer, larger capacity 64GB cards are formatted as exFAT. The fact that you have re-formatted it as NTFS may have something to do with your problem.

4

Thanks. I’ll try reformatting it tomorrow. This happened before the reformat though, the format was just an extreme example of it ‘forgetting’ what had been written to it.

5

Nope. Reformatted it as exFAT and the same thing happens. It sits formatting for about an hour, before a 'Format complete; message pops up. If I open it in Windows Explorer, it shows up as blank, with 59GB free, exactly as you’d expect.

I can read and write to/from this, save files there, view them, copy them back, everything you’d expect.

However as soon as I unplug the card and reconnect it, it’s back *exactly* as it was before the format, showing all the files it held previously.