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

[Dale]

Mark Knecht wrote:
> On Wed, Dec 29, 2021 at 10:14 AM Dale <rdalek1967@×××××.com> wrote:
>> Mark Knecht wrote:
>>> <SNIP>
>>>> So while rare, it's not just me.  ;-)  I've had cards fail by just plain
>>>> refusing not to mount at all, mounting read only and such.  I've never
>>>> had one to fail like this tho.  I guess if this was some sort of
>>>> sensitive files, I'd have to put it in a shredder or take a pair of
>>>> scissors to it.  LOL
>>>>
>>>> I ordered 6 new cards as replacements.  They came in yesterday.  Like I
>>>> said, I wouldn't trust that card even if it started working again.  So,
>>>> off to the trash the weird card goes.  Now I just have to wonder why dd
>>>> and such didn't report problems.  :/
>>>>
>>>> Thanks to all for the info.  Interesting.
>>>>
>>>> Dale
>>>>
>>>> :-)  :-)
>>>>
>>> Actually, it's possible that it failed this way by design. What if the
>>> card recognized that it's in some sort of a wear out condition and
>>> just shut off new writes? One might see it as a failure but a
>>> different view is as a potential opportunity to retrieve data before
>>> it's gone.
>>>
>>> You might want to check out this tool:
>>>
>>> https://github.com/BertoldVdb/sdtool
>>>
>>> which advertises that it can view, set and reset the write protection
>>> status of an SD card. Can't hurt if you're committed to throwing the
>>> device in the trash can anyway. (Well, it could possibly hose your
>>> system if you use it incorrectly or if it has bugs, but that's true
>>> about all software, right?) ;-)
>>>
>>> But at least you could view the status of the card.
>>>
>>> Cheers,
>>> Mark
>>>
>>>
>>
>> I downloaded sdtool but I don't have the required devices in /dev to use
>> it.  In the readme it says not to use /dev/sd* but to use /dev/mmcblk*.
>> It seems my card reader doesn't connect in a way for those to be
>> created.  Would have been nice just to see what it does tho.  I still
>> wouldn't trust it of course but being curious . . . .
>>
>> By the way, the card is a Sandisk which has a fairly good reputation.
>> It is possible that it failed in the best way it could.  On the positive
>> side, it did fail in a way that the files could be recovered.  That's
>> always a good thing.  It's certainly better than failing with no way to
>> get the files.
>>
>> Dale
> OK, sorry it's not easy. I suppose now that you are using some sort of
> USB bridge for reading your SD cards? That probably makes it show up
> as a standard /dev/sd device like other USB drives.
>
> I may be wrong, and it might not help you, but I think /dev/mmc is
> enabled through the MMC_BLOCK option in the kernel, but even if you
> enable that it may not change things if you have a USB bridge in the
> way.
>
> On Windows there are some partition editors that show the state of
> these bits. I haven't looked for a standard Linux partition editor
> that does that but it's probably out there somewhere if you go
> hunting.
>
> If you own a DSLR that supports whatever size SD card you are using
> then it probably has a way to write protect cards while in the camera.
> However if it's just a web cam that you're using it probably doesn't
> but check the documentation.
>
> Good luck,
> Mark
>
>


Those deer trail cameras are somewhat cheap, ish.  Some of them don't
even have a format option.  I have a old camera that the IR sensor
doesn't work on, it never knows something is there to take pictures of
so it does nothing.  Anyway, I use it to format cards with since most
all trail cameras use the same format type and directory tree.  One
partition and vfat.  Basically, it is really simple and not a lot of
options. 

I use a card reader that hooks up via USB.  It's one of those multi
reader thingys.  It's been a pretty good one but it isn't a real
expensive one either.  Given I got the data off and plan to trash it
anyway, it's not worth recompiling a kernel, rebooting and then hoping
it will have the right device thingys. 

This thread has been interesting tho.  At least I know that a Sandisk
card at least tries to fail in a way that I can get the data off that
did get written to the card.  Hey, that's a lot better than some I
guess.  :-D  I've had some other brands that when they die, they dead. 
You get nothing at all. 

Dale

:-)  :-)