Copying a disk image onto a CF card using Unix dd is a trivial task (unless you make a mistake when specifying the output file (the of= option) – recovery from that kind of mistake can be a bitch. ;-) )

    dd if=disk.image of=/dev/da0

dd starts copying with a default blocksize of 512 bytes.

Copying a 4 GB image on the weekend took almost three hours. (153 minutes to be precise.)

On the next run, I used a block size (both on input and on output – dd can control these separately) of one megabyte, thereby reducing the duration of the copy to just over 6 minutes.

    dd if=disk.image of=/dev/da0 bs=1m

Sometimes, old-fashioned defaults are just, well, old fashioned. :-)

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Linux, CLI, BSD, and cf :: 25 Jan 2010 :: e-mail


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