Hard Drive data rates
Aaron Konstam
akonstam at sbcglobal.net
Fri Sep 28 20:57:47 UTC 2007
On Fri, 2007-09-28 at 12:07 -0700, John Wendel wrote:
> Lamar Owen wrote:
> > On Friday 28 September 2007, Karl Larsen wrote:
> >> I was lead to mis-understand the data rate of my new SATA hard
> >> drive. It indicated that the data rate was 3 GB/sec. But some checking
> >> with Google said the Hard Drive makers are very free with their units.
> >> To be specific a SATA drive is 3000 MegaBits/second. This boils down to
> >> about 375 MB.
> >
> > Due to the 8B/10B coding used in SATA, you can divide the bitrate by ten and
> > not eight to get the byterate. Thus, 3Gb/s is 300MB/s at the wire. The
> > semi-standard way of differentiating between bits per second and bytes per
> > second in specs is to use a lower-case b for bits, and an upper-case B for
> > bytes, but unfortunately not everyone follows that.
>
> Your talking about the wire speed. The REAL speed is determined by the
> disk drive. You're lucky to get 75MB/s with a desktop drive.
>
> Regards,
>
> John
Try hdparm -T and hdparm -t
--
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It is much easier to suggest solutions when you know nothing about the
problem.
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Aaron Konstam telephone: (210) 656-0355 e-mail: akonstam at sbcglobal.net
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