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I have a microSD sandisk Extreme with 64GB, that I use with my phone. I store around +70000 files on it, many small.
The problem I have is that my phone keeps unexpectedly unmounting the card, reporting that the card is blank (!!) or damaged. But the card gives errors even outside of a phone: also my linux box gives errors when I mount the card on it, specially if I try something like badblock command line, independently if it was previously used or not in a phone. So, this is not a phone-related problem. fsck command and its exfat version shows no filesystem error.
Then, I erase everything, format it, and run badblock -w on it, which is a hard test: after 15 hours writing and reading the card, no errors, no umounting, it seems as good as new. If I copy everything back to the card it works well, until certain point that I have to reformat it again.
So, what is happening? Is this a limitation due to fragmentation in exfat when using too many files, or is my microSD card somehow broken? Can I trust it?
Luis A. Florit
Posted 2017-07-08T22:51:09.787
Reputation: 151
Phone problems are not on topic here. – Xavierjazz – 2017-07-09T02:02:57.367
If the problem occurs with the card when you use it on your computer, it would be on-topic. However, the problem would be a defective card and there's no solution for it. If the problem only happens with your phone, the problem might be with the phone rather than the card. However, that would be off-topic for the site. The symptoms do sound phone-related because cards don't usually fail in that manner. – fixer1234 – 2017-07-09T05:09:55.113
No, it is not phone related, as I wrote. The card gets ejected when trying to copy lots of data to the card, or with a
badblockcommand, in my Linux desktop, outside of the phone. However, if I reformat the card and put the data back, it works just fine. I even runbadblocks -wwhich took +15hours of constant write and read with 0 errors after reformatting.... Could it be something like fragmentation? Is this related to exfat? – Luis A. Florit – 2017-07-09T05:19:57.5232Attention, speed-readers: The question says, "So does my linux box when I mount the card on it..." So it appears to be about computer software and computer hardware. – G-Man Says 'Reinstate Monica' – 2017-07-10T04:17:06.000
@G-Man, after a careful read, my understanding is that the card messes up only after being in the phone first. It gets cleaned up on the computer, goes back in the phone, and then is corrupted again in the phone. It sounds like the corruption is happening in the phone. The cards generally don't repeatedly fail and heal themselves; when they fail, it's permanent. The card also doesn't fail in the computer until after it's been in the phone. If that's not the case, that critical diagnostic information should be clarified. – fixer1234 – 2017-07-10T16:31:00.250
Attention @LuisA.Florit: Your question is at risk of being closed. Please read these comments and [edit] your question to clarify it. (Do not respond in comments.) – G-Man Says 'Reinstate Monica' – 2017-07-10T20:13:12.073
@fixer1234: question edited trying to be more explicit. – Luis A. Florit – 2017-07-11T15:06:33.817
@LuisA.Florit, it sounds like the card has problems only after it has been in the phone. which would point to the phone corrupting it. The card, itself, probably isn't the problem. Does the card misbehave after reformatting if you only use it in the PC and don't put it back in the phone? – fixer1234 – 2017-07-11T15:33:01.073
@fixer1234: actually, the card is not being corrupted. No errors are reported. It just keep being unmounted (that eventually can corrupt it of course). If I empty and reformat the card, it works perfectly. I put back all the files and work fine for some weeks, and then it begins to being unmounted unexpectedly, both in the phone and in the Linux box.But I indeed use it exclusively in the phone, the linux problem happens when I try to run
badblockson it, or transfer lots of files with the card mounted on the box (something that I almost don't do). – Luis A. Florit – 2017-07-12T00:41:43.083@LuisA.Florit, does the card ever misbehave if you clean it up and then use it only on the PC so the phone never touches it? – fixer1234 – 2017-07-12T01:19:25.430
@fixer1234: never tried that... – Luis A. Florit – 2017-07-12T01:42:32.953