Re: [gentoo-user] {OT} USB 3.0 hard drive speed test

[Volker Armin Hemmann]

Am Donnerstag 11 August 2011, 10:12:54 schrieb Grant:
> I'm testing this USB 3.0 bus-powered hard drive:
>
> http://www.amazon.com/gp/product/B0041OSQ9S
>
> and I get:
>
> # hdparm -tT /dev/sdb
> /dev/sdb:
> Timing cached reads:   8006 MB in  2.00 seconds = 4004.33 MB/sec
> Timing buffered disk reads: 252 MB in  3.01 seconds =  83.63 MB/sec
>
> # hdparm -tT /dev/sdb
> /dev/sdb:
> Timing cached reads:   8230 MB in  2.00 seconds = 4116.54 MB/sec
> Timing buffered disk reads: 252 MB in  3.02 seconds =  83.55 MB/sec
>
> # hdparm -tT /dev/sdb
> /dev/sdb:
> Timing cached reads:   8446 MB in  2.00 seconds = 4224.36 MB/sec
> Timing buffered disk reads: 230 MB in  3.02 seconds =  76.28 MB/sec
>
> Wikipedia says USB 3.0 has transmission speeds of up to 5 Gbit/s.
> Doesn't MB/sec denote mega*bytes* per second?
>
> - Grant

so what?

first you are measuring the access to the in-memory cache and then a harddisk 
- and for a harddisk 80mb/sec is really, really good.


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#163933