Hard Drive data rates

[Dave Stevens]

On Friday 28 September 2007 10:50:32 am 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.
>
>     The old standard IDE parallel 40 pin plug is rated for a rate of 112
> MB at the fastest to 78 GB at the slowest part of the platter. So in my
> case I will not see a huge change moving to my SATA hard drive. I will
> stay here on the new IDE much longer.

I'd be very interested in seeing the command and output for that drive using 
hdparm -iItT

>
>
> --
>
> 	Karl F. Larsen, AKA K5DI
> 	Linux User
> 	#450462   http://counter.li.org.

Karl,

I use a Seagate 320 gig ES SATA drive. This is a 3 Gb/sec drive BUT - it was 
shipped with a jumper installed limiting it to half that rate, and this rate 
is in any case a very optimistic one. Using hdparm as suggested consistently 
gives me 78 MB/sec. That seems to be as good as it gets. Also this is a very 
artificial figure, I have an old (about ten years) 9 gig SCSI drive that does 
about half that. It seems that the recent addition of NCQ to SATA drives 
makes more of an improvement in heavily loaded scenarios but quantifying this 
is not simple or unambiguous. I want to try reconfiguring this setup in raid 
0 but won't be able to do so for a while. I know that another recent Seagate 
drive, their 400G ATA gives transfer rates using hdparm -tT of about 50 
MB/sec.