usb speed, is this correct?

ste_bla · 4 Nov 2006 at 00:04

I send a file that is 470mb and it takes 17 seconds

so thats 27mbps isnt it?

I thought usb2 ran @ 480 mbps and usb1 ran at 12mbps..

So is it usb2 just running REALLY slowly?

hohum · 4 Nov 2006 at 00:18

It's because USB 2.0 has a max speed of 480 megabits, not megabytes. Also, you don't say what you're sending it to... other factors come into it aswell, such as the read/write speed of the storage media being used and whatnot.

Jokester · 4 Nov 2006 at 00:26

USB also has quite a big overhead if I remember correctly so actual throughput will be a bit less than 480Mbps that again.

Jokester

ste_bla · 4 Nov 2006 at 00:44

Okay so USB 2 is rated max 480 megabites per sec which is 60megabytes per second..

So half the maxium possible bandwibth..

looking on the Lacie website just now and it says;

Max Sustained Transfer Rate : up to 34MB/s with Hi-Speed USB 2.0

So i guess thats close to the 27 figure I have..

So i guess theres no problem

One other question the usb transfer uses 25% usage this seems a hell of a lot as it only uses 35% to record from my tv card! Is that normal?

Rroff · 4 Nov 2006 at 00:47

A lot of people seem to have trouble getting USB2 to sustain high transfer rates... I found on my current rig any one USB2 port would cap out at about 25-30MB/s (200Mbit or so) but if I was using 2 ports at the same time, even if they were connected to the same root hub, I could get a combined transfer rate of 380-400Mbit/s sustained (when backing up my raid0 array to 2 different external HDDs)