dd vs. cat >/dev/xxx

Taavi Burns taavi-LbuTpDkqzNzXI80/IeQp7B2eb7JE58TQ at public.gmane.org
Wed Dec 10 15:27:10 UTC 2003

On Wed, Dec 10, 2003 at 12:26:03AM -0500, Justin Zygmont wrote:
> just a quick question here, I was wondering if there is really much 
> benefit from using dd to image a floppy disk than cat >/dev/fd0.

With correct options, dd will go a LOT faster.

dd if=yourfile.img of=/dev/fd0 bs=64k

Be sure that bs is a multiple of your device's sector size, or
you'll really hurt performance.  Floppy sectors are only 512 bytes,
but buffering (i.e. doing IOs in blocks of) at that size is highly
inefficient.  64k seems to work nicely for me...I seem to vaguely
remember 18k being optimal, though (one full track).

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