Re: [gentoo-user] SD memory card not erasing, even with dd.

[William Kenworthy]

On 29/12/21 20:26, Michael wrote:
> On Tuesday, 28 December 2021 20:21:32 GMT Dale wrote:
>> Howdy,
>>
>> As some may recall, I have quite a few deer trail cameras that use SD
>> memory cards.  On occasion some of the cards start acting weird.  I've
>> got one that is really weird.  Usually I just replace them but this one
>> is a bit of a puzzle I'd like to solve.  When it stopped working, it had
>> a dozen or so short videos on it that are about 30MBs on average.  Some
>> color and large, some black and white night vision and fairly small.
>> When it stopped working, I tried to reformat the thing.  The files
>> remained even after that.  I then ran dd and zeroed the thing, files
>> still there even tho dd reported no problems.  I then used this GUI disk
>> program that tests memory cards and it claims the card is fine.  It
>> writes files to it, reads them back.  I also used it to reformat the
>> card.  The original videos are still there.  Today I decided to play
>> with it again.  I ran this dd command on the stick.
>>
>>
>> root@fireball / # dd if=/dev/zero of=/dev/sdh bs=4K conv=notrunc
>> oflag=direct status=progress
>> 31907364864 bytes (32 GB, 30 GiB) copied, 3956 s, 8.1 MB/s
>> dd: error writing '/dev/sdh': No space left on device
>> 7791745+0 records in
>> 7791744+0 records out
>> 31914983424 bytes (32 GB, 30 GiB) copied, 3956.94 s, 8.1 MB/s
>> root@fireball / #
>>
>>
>> As you can see, no errors. It wrote zeros until it ran out of space.
>> Guess what, the original videos are still on the card.  File listing:
>>
>>
>> root@fireball / # ls -al /run/media/dale/2140-2E00/DCIM/100MEDIA/*
>> -rw-r--r-- 1 dale users        0 May  6  2018
>> /run/media/dale/2140-2E00/DCIM/100MEDIA/AAAAAAAA.AAA
>> -rw-r--r-- 1 dale users        0 May  6  2018
>> /run/media/dale/2140-2E00/DCIM/100MEDIA/BBBBBBBB.BBB
>> -rw-r--r-- 1 dale users 14335272 May  2  2018
>> /run/media/dale/2140-2E00/DCIM/100MEDIA/WGI_0823.AVI
>> -rw-r--r-- 1 dale users 50843576 May  6  2018
>> /run/media/dale/2140-2E00/DCIM/100MEDIA/WGI_0824.AVI
>> -rw-r--r-- 1 dale users 53137560 May  6  2018
>> /run/media/dale/2140-2E00/DCIM/100MEDIA/WGI_0825.AVI
>> -rw-r--r-- 1 dale users 18398504 May  6  2018
>> /run/media/dale/2140-2E00/DCIM/100MEDIA/WGI_0826.AVI
>> -rw-r--r-- 1 dale users 18922808 May  6  2018
>> /run/media/dale/2140-2E00/DCIM/100MEDIA/WGI_0827.AVI
>> -rw-r--r-- 1 dale users 18332888 May  6  2018
>> /run/media/dale/2140-2E00/DCIM/100MEDIA/WGI_0828.AVI
>> -rw-r--r-- 1 dale users 18726200 May  6  2018
>> /run/media/dale/2140-2E00/DCIM/100MEDIA/WGI_0829.AVI
>> -rw-r--r-- 1 dale users 18332920 May  6  2018
>> /run/media/dale/2140-2E00/DCIM/100MEDIA/WGI_0830.AVI
>> -rw-r--r-- 1 dale users 18005288 May  6  2018
>> /run/media/dale/2140-2E00/DCIM/100MEDIA/WGI_0831.AVI
>> -rw-r--r-- 1 dale users 17612088 May  6  2018
>> /run/media/dale/2140-2E00/DCIM/100MEDIA/WGI_0832.AVI
>> -rw-r--r-- 1 dale users 17153336 May  6  2018
>> /run/media/dale/2140-2E00/DCIM/100MEDIA/WGI_0833.AVI
>> -rw-r--r-- 1 dale users 16694584 May  6  2018
>> /run/media/dale/2140-2E00/DCIM/100MEDIA/WGI_0834.AVI
>> -rw-r--r-- 1 dale users        0 May  6  2018
>> /run/media/dale/2140-2E00/DCIM/100MEDIA/WGI_0835.AVI
>> root@fireball / #
>>
>>
>>
>> The zero byte files are broken, my first clue way back that the card
>> needed replacing.  I see no errors in dmesg or messages.  Usually the
>> cards produce errors and it remounts read only.  Not in this case tho.
>> Mount info:
>>
>>
>> root@fireball / # mount | grep sdh
>> /dev/sdh1 on /run/media/dale/2140-2E00 type vfat
>> (rw,nosuid,nodev,relatime,uid=1000,gid=100,fmask=0022,dmask=0022,codepage=43
>> 7,iocharset=iso8859-1,shortname=mixed,showexec,utf8,flush,errors=remount-ro,
>> uhelper=udisks2) root@fireball / #
>>
>>
>>
>> In the past, I've at times been able to copy the files off other cards
>> going bad but it stays read only.  Reformating fails etc etc.
>> Sometimes, it just plain doesn't work.  Almost always tho I get a error
>> of some kind in messages or dmesg if not both.  This one tho, it's just
>> plain weird.  No errors but nothing removes the files either.  Oh, I've
>> checked the lock button.  It's not locked.  It is shown that way in
>> dmesg as well.
>>
>>
>> [2592841.808336] sd 10:0:0:2: [sdh] Write Protect is off
>>
>>
>>
>> Obviously I'm not going to trust this thing.  It will end up in the
>> trash but, does this make sense to anyone else?  Of all the ones I've
>> worn out, this is the only one that behaves this way.  I'd at least
>> expect the format to fail or it only mount read only.  At least some
>> sort of error anyway.
>>
>> Thoughts?
>>
>> Dale
>>
>> :-)  :-)
> I don't think I've come across something like this before.  In my case data is
> lost, occasionally irretrievably.
>
> I suppose something has switched blocks on the SD as immutable, probably a
> controller having a hiccup.
>
> You could try blkdiscard to erase blocks directly - but I haven't tried this
> on an SD.  I also haven't tried to know if it will work at all hdparm's secure
> deletion.
>
> However, the best option is to see if the OEM offers a reset app for this
> particular card and use that.

I have a few SD cards as OS disks on raspberry pi, odroids etc. One has 
your symptoms like yours - read only when it says its in write mode.  
Took two days after the last write to syslog to drop dead - just before 
Christmas too, luckily it was part of a moosefs cluster so I could leave 
it in maintenance mode without affecting service - replaced today.  No 
salvaging it unfortunately - also not the first one that I have had die 
like this.  I tested some others and have one thats really slow when 
dd'ing zeros to clear vacant space (I think that's redundant for SD 
cards, better to trim it?) before making a compressable backup image.  
It also drops to RO with no errors in syslog before completing.  So I am 
down 2 cards and need to order some more spares before another fails :(

BillK