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

[Michael]

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.