08-16-2017 12:03 PM - edited 08-16-2017 12:06 PM
Yup. My 64gb Ultra micro SD card is dead as well. Write only. Old content can be read but deleting/formatting does nothing. Really disappointed to have 2 Sandisk products fail on me this year.
02-21-2018 06:42 PM - edited 02-21-2018 06:44 PM
Just purchased SanDisk Ultra PLUS micro SDXC UHS-1card with adapter 200Gb up to 100MB/s for $79 from WalMart. It worked great for awhile, while trying it in several laptops in micro and with adpapter modes. Then I put it in a cheap $10 USB Made in China adabter/read/writer in both micro and Adapter mode. It worked in everything i put it in except at some point it started reading 31.8Gb instead of the 183Gb that it originally started out with. I tried formating on several machines using every format I could and even using "restore defaults" with no luck. Then I googled the problem and ended up on this thread. One of the suggestions was to download the SD formatter from the SD Card Association. I didnt even know there was an SD Association. I down loaded the free formatter, popped the card in and it immediately recognized it as a 200Gb xFAT 128Kb Byte size card. Formated just fine. Im using a $210 HP laptop with AMD A6 9220 processor/Windows10 Home build 1709, which will apparently read and write to the card fine but comes up short if at some point you decide to wipe it clean and reformat. Get the free format software from the SD Card Association!
08-20-2018 12:53 PM
I find it is now 5 years since this card type (micro sdxc 64GB) is causing problems.
I bought 3 in the last 2 years, without really informing / documenting the problems of Sandisk cards very seriously before. Two of them died. Same symptoms: it can not be written on either (neither move, nor delete, nor format, nor low-level formatting, no change to the partition type ...). I've tried many softwares (including SD Card Formater from SD org recommended here). I even tried the diskpart command to change the card attributes ... The card has exactly the same behavior in Windows, in Android phone, or in Canon camera. Any changes to the card content are blocked, but reading can be done.
10-21-2018 04:39 PM
I have tried everything including the SD Card Formatter and nothing works. No matter which "solution" I try either it fails outright or in the case of copying or deleting files it appears to work but if I remove the SD and reinstert it everything is as it was before. The part that is weird is that I have two of the 64Gb SDXCs and both have exactly the same problem. I even put the thing against a super magnet I have is nothing happened. Apparently magnetism is not used for storing data anymore. It seems my soluting is to run the things through my paper shredder and buy a different brand of SD card, unless there is something I haven't tried yet.
02-16-2019 08:36 PM
Ah, after all these years I find that the problem is with this actual product. Normally I recommend Sandisk and I still do, but not the 64GB SDXC anymore. I've mostly used these in phones where they end up failing but I also design embedded control systems and integrate various SD and microSD cards into the product as well as write the file system software to acces them including the low-level drivers and SD commands. I was implementing format utilies to force 64GB cards to format to FAT32 but the one and only 64GB card I had that seemed to work fine in that I could read all the files off it that I had in my phone, just would not format.
Investigating this right down at the low level (in SPI vs SD mode) I see that the card responds to the write command CMD24 and follows through as if everything wrote to the 512 byte sector (SD cards are actually accessed as 512 byte "sectors" or blocks), and the response from the card says everything is fine, but a check reveals that nothing was written. Of course I also tested these with the SD Card Associations's formatter including one from Paanasonic and other utlities as well, but no luck, either now, or with other cards in the past.
Just in case there has been a silent revision from Sandisk this is part of the internal information that I read in my system - for reference this is a SU64G revision 128 or $80 and rather an old one from 2013 it seems. My guess is that from my electronics engineering background that an internal "charge-pump" that boosts the voltage needed to erase Flash has failed and would result in these symptoms.
CARD: SANDISK SD SU64G REV$80 #2920609953 DATE:2013/5
03-20-2019 05:02 PM
Does anyone have the default heads & cylinders numbers from a HEALTHY Ultra 64 micro SDXC? Am getting complaints from Linux that things don't match. Hoping this isn't yet another such failure.