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Re: dd to clone a drive




On Tuesday 26 September 2017 09:57:57 Jack Dangler wrote:

> I have an existing drive near EOL (judging from the sounds). I got a
> replacement drive for it (same size).
>
> I plugged the replacement into a USB port and started a byte-for-byte
> copy with
>
> dd if=/dev/sda of=/dev/sdc
>
> The process ran quietly for almost 30 hours with no discernable
> results so i killed it. Apparently, it had been running the whole time
> and resulted in approximately 300 of 500Gb copied. Is it 'usual' to
> have dd take upwards of 2 days to copy a drive ?
>
> The source drive is a 500G 5400rpm WD, and the target is a 500G
> 7200rpm WD black.
>
> Thanks for any input.
>
I think when no bs size is specified, it does a sector copy and likely 
verifies it. In writing sd cards in a usb reader/writer here, dd's 
execution time can be cut to maybe 5 minutes for a 2GB image by the use 
of the "bs=4096" option in the above command line.  That should mean 
your 500GB copy operation would take about 20 hours, probably much less 
since the hd can write faster than my sd cards can on a sustained basis 
like 500GB.

> Regards
>
> Jack


Cheers, Gene Heskett
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