Hard Drive data rates

[John Wendel]

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