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Re: Unusable system during dd to USB block device (Arto Huusko) writes:

>The transfer did work, but it was excruciatingly slow, under 2 Mb /
>sec. But that wasn't the only problem: it also made most other
>activities on the system unusable, at least if there was any disk
>access involved.

The block devices pass things through the traditional buffer cache
which adds lots of overhead and splits everything into small I/O
fragments. The cache is also flooded with stale data, making it
completely useless and everyone else has to compete with your
mass I/O requests.

                                Michael van Elst
                                "A potential Snark may lurk in every tree."

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