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Re: dd to clone a drive




Hi,

> Is it 'usual' to have dd take upwards of 2 days to copy a drive ?

Not really. An old 500 GiB SATA disk may deliver about 50 MiB/s.
That's 10000 seconds, a bit less than 3 hours.
(If you copy from filesystem to filesystem it may last much longer
 due to the lookup times in the trees.)

The first suspect for slow dd is small block size.
So you should in any case ask dd for larger chunks as already proposed
by Michael Stone. For copying Debian ISOs to USB sticks the FAQ proposes
4 MiB. But i think 1 MiB is surely enough:

  dd if=/dev/sda of=/dev/sdc bs=1M

Next you should get some progress indicating pacifier.
I see that Roberto C. Sánchez already showed the USR1 method to make dd
print progress.
Here is another way:

  dd if=/dev/sda bs=1M | pv | dd of=/dev/sdc bs=1M

(With if=/dev/zero and of=/dev/null i get 5 GiB/s here. So the pipes
 are not a problem in respect to throughput.)


Have a nice day :)

Thomas