[PLUG] Weird microSD failure

[Tim Garton]

Don't you need a "count=#" option to dd as well? Not at a computer right
now otherwise I'd be able to check if that's the case...

On Mar 6, 2018 5:02 PM, "Richard England" <rlengland at frontier.com> wrote:

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