I have a microSD card ("Lexar microSD RDR", according to Linux) which I previously used as "internal storage" for my Android 6 phone. However, at some point, I had to factory reset this phone; after which my phone did not longer recognise the SD card as internal storage; nor was it able to format the card.
Note: I only used the card for about 3 months as internal storage. Everything worked perfectly fine up until the factory reset, no physical damage was done to the card, and it should definitely not be near its lifespan yet.
What I've tried so far on Windows 10:
- Try right-click and format. While it's a 16GB disk, Windows claims it only has a 16 MB volume (see later); and formatting it this way always fails: "Windows was unable to complete the formatting".
- Opening Disk Management reveals this disk has 2 primary partitions: a 16 MB one; and a 14.90 GB one. Both are listed as healthy. However, trying to "Delete Volume" on either of them does nothing.
- Using DiskPart, I selected the disk, tried both "clean" and "clean all". DiskPart claims both worked ("DiskPart succeeded in cleaning the disk"), but nothing actually happens. I cannot create a new primary partition afterwards ("The operation is not supported on a non-empty removable disk").
Note that there were no flags like readonly turned on! - Tried adding the registry key "Write Protect" under "Storage Device Policies" and restarting the computer; then repeating all the previous. No results.
- Tried different card readers, both with and without those lock switches on the side.
What I've tried so far on Linux Mint 18.1:
- Look in Disks, which shows me the same two partitions as before, but now with the names "android_meta" and "android_expand". Trying to delete either of them does nothing.
- Tried the same with GParted. Deleting both partitions apparently works, but they instantly reappear.
- Tried the same with fdisk, again, same results.
So, long story short: I seem to be completely unable to format the sd card. I don't care about the contents; I would just like to be able to use it again.
Best Answer
I understand not all formatting programs are made equal, especially with regard to the handling of the security features of the SD/SDHC/SDXC protocols.
Firstly, if you know the exact brand / model /protocol, look for a specific formatting program on the manufacturer site. In your case, i would double check that what is written on the card fits what linux detected and start from there. This is your best chance to be able to access the protected area of the SD/SDHC/SDXC card and fully reformat it.
Second, you may want to try software like SD Card Formatter 4.0 that is supposed to be better than OS native formatting software for SD cards.
Some caveats (cf wikipedia link below): Reformatting an SD card with a different file system, or even with the same one, may make the card slower, or shorten its lifespan. Some cards use wear leveling, in which frequently modified blocks are mapped to different portions of memory at different times, and some wear-leveling algorithms are designed for the access patterns typical of FAT12, FAT16 or FAT32. In addition, the preformatted file system may use a cluster size that matches the erase region of the physical memory on the card; reformatting may change the cluster size and make writes less efficient.
You can find more details on this wikipedia page