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Re: Hard Drive data rates



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


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