[sclug] disk transfer rates (was) Newbie, partitioning 120Gb HDD - recommendations?

Tom Dawes-Gamble tmdg at tmdg.co.uk
Wed Jan 19 12:02:58 UTC 2005

On Wed, 2005-01-19 at 10:09 +0000, Dickon Hood wrote:
> On Wed, Jan 19, 2005 at 07:52:42 +0000, Tom Dawes-Gamble wrote:
> [...]
> : So I've knocked together a very rough benchmark. How long so it take to
> : read a gigabyte from the disk.  I did each test several times and these
> : are typical results.
> Try hdparm -T and -t; they're more accurate than any number of runs of dd,
> as it bypasses the OS caches.

More accurate for what?

Personally I like using dd to measure I/O.  It's a nice userland
programme.  Almost all the stuff I do is run in userland.  If the OS
caches data and reads ahead such that I don't notice any difference or
the difference is reduced.  Then I say "Well done!  Thank you".


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