[PLUG] Weird microSD failure

[Richard England]

On 03/06/2018 04:20 PM, Tomas Kuchta wrote:
> Try to delete the original files first. Then create empty file using
> /dev/zero and copy it to the card. I bet that it will be there on the card
> and some of your original data will disappear as result.
>
> My guess is that the card controller is deduplicating your /dev/zero blocks
> trying to protect the card from writes.
>
> Tomas
>
> On Mar 6, 2018 7:09 PM, "Russell Senior" <russell at personaltelco.net> wrote:
>
>> On Tue, Mar 6, 2018 at 3:04 AM, Russell Senior
>> <russell at personaltelco.net> wrote:
>>> On Tue, Mar 6, 2018 at 3:01 AM, Jim Karlock <jjkarlock at gmail.com> wrote:
>>>>> My initial attempt to google this was unsuccessful (most people point
>>>>> out the write protect tab, not my problem).
>>>>
>>>> Bad switch on the write protect tab? (The tab operates a tiny switch.)
>>> Nope.
>>>
>>> I can turn the switch to lock and it mounts the device read only very
>>> clearly.  The behavior I observe is that it happily writes /dev/zero
>>> over the block device, but then when I read again, the old data is
>>> still present.
>> For example, if I flip the tab to write protect tab to "Lock", I get this:
>>
>> # dd if=/dev/zero of=/dev/sdc status=progress bs=1M
>> dd: failed to open '/dev/sdc': Read-only file system
>> _______________________________________________
>> PLUG mailing list
>> PLUG at pdxlinux.org
>> http://lists.pdxlinux.org/mailman/listinfo/plug
>>
> _______________________________________________
> PLUG mailing list
> PLUG at pdxlinux.org
> http://lists.pdxlinux.org/mailman/listinfo/plug

|Perhaps using dd if=/dev/urandom |of=/dev/sdc status=progress bs=1M
...just a thought.