Problems from the other side with MicroSD cards
Problems from the other side with MicroSD cards
I possess a 400GB SDXC card from SanDisk that doesn’t store any information. (Including the partition table) Windows rejects it and closes Explorer (three separate machines, one with AME). Linux recognizes the card, identifies its correct size, and assigns it /dev/mmcblk0 without issues. No problems occurred across four different computers, using various card readers, running Arch, Debian, Ubuntu, Manjaro, and Gentoo with unchanged kernels. The odd thing in Linux is that writing from /dev/random to the card with dd (using dd if=/dev/random of=/dev/mmcblk0) works fine—no errors, even after running it for a minute. When I try to read back the data (cat /dev/mmcblk0), only zeros appear. I also experimented with writing data back via dd to a file (dd if=/dev/mmcblk0 of=randomfile) and observed only zeros in the hex viewer, with no errors from dd. The logs show nothing unusual, and nothing appears to be throwing exceptions. I suspect the card is failing but I want to understand what’s wrong and learn more about MicroSD cards. Something else useful would be guidance on enabling debugging for the mmc drivers.
Alright, understood. It seems like they're just failing now. I don’t have enough info to guide you on enabling debugging, but I figured I’d mention the 'fake' option since I’ve had issues with fake cards before.