On Mon, 7 Oct 2019 at 02:48, Samuel Sieb <samuel@xxxxxxxx> wrote:
On 10/6/19 8:50 PM, jdow wrote:
> On 20191006 01:34:45, Tom H wrote:
>> On Sun, Oct 6, 2019 at 9:05 AM ToddAndMargo via users
>> <users@xxxxxxxxxxxxxxxxxxxxxxx> wrote:
>>>
>>> Fedora 30 x64
>>>
>>> # dd bs=4096 if=/dev/sdb of=/dev/dull status=progress
>>> 8301694976 bytes (8.3 GB, 7.7 GiB) copied, 38 s, 218 MB/s
>>> dd: error writing '/dev/dull': No space left on device
>>> 2034754+0 records in
>>> 2034753+0 records out
>>> 8334348288 bytes (8.3 GB, 7.8 GiB) copied, 38.4257 s, 217 MB/s
>>>
>>> /dev/null is full ??? Huh ???
>>
>> 1) "/dev/null" not "/dev/dull"
>>
>> 2) "if=/dev/null of=/dev/sdb" not "if=/dev/sdb of=/dev/null"
>
> Don't you hate it when you do that (item 2), Tom?
He did have them in the right order.
"if=/dev/null of=/dev/sdb" would do nothing at all.
Not "nothing", Flash memory cells have a limited number of writes.
Devices based on flash memory use several strategies,
including wear leveling and spare capacity so failed regions
can be replaced with fresh cells. Flash devices that get a lot
of writes will last longer if they are kept well below the maximum
capacity, and should have a command to "delete" all the data
that doesn't actually overwrite the existing data. Using
"count=N if=/dev/null of=/dev/sdb" to zero out the partion table and
boot "sector" is easy and shouldn't cause a lot of wear since those
areas shouldn't change often.
High-end flash memory sticks should have self-monitoring and
testing (SMART) capabilities. See:
Many vendors provide utilities (often on a freeDOS CD) to manage their USB
sticks.
George N. White III
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