usb speed troubles

D

ddanj

n00b
Joined
Sep 24, 2004
Messages
17
So I got a new 8gb sony microvault. I'm getting the following speeds on it:

for a 760MB files:
onto the usb drive: 135s, ~5.6MBps=~45Mbps
off the usb drive: 40s, ~19MBps=~152Mbps

where is the 480Mbps (60MBps) ?? I know that is probably for ideal conditions, but still, I'd still expect more then what I'm getting.

stats:
USB 2.0 capable mobo (MSI KT880)
ATA133 7200rpm Hitachi hard drive
1.6Ghz Athlon XP
1gig of corsair ram
Win XP (SP2)

any help would be much appreciated
 
You expect 480mbps?
Where did you read that it should be that fast?

Those speeds are fine.
 
The USB 2.0 bus is rated at 480mbps, the memory stick isnt.
 
how do you know? it says USB 2.0 on it.

Is there a way to verify this? if it IS a USB drive problem, or a computer/driver problem?
 
ddanj said:
how do you know? it says USB 2.0 on it.
Click to expand...
That means it's compatible with the USB 2.0 specifications. That does not mean it maxes out USB... I would add for the record that the FIRST SATA standard is 1.5GB/s (with SATA 3.0 being 3.0GB/s) but you don't see any harddrives delivering that... At least, not normal harddrives (perhaps a solid state drive could?) So obviously being compliant with a specification does not mean it meets the maximums of that specification. In fact, many companies prefer to meet the minimum due to it being notably cheaper to do so.

Though the specs claim that USB 2.0 can deliver 480Mbps, that's assuming absolute best case scenario, AND it refers to short bursts. Long sustained transfers will tend to max out more around the range of some 200Mbps or so. And that's only when the drive itself can actually handle this and the bus has no other drives. (Besides having seen many reviews confirming this 200Mbps approximation, I have tested via a relatively fast SATA drive plugged into USB 2.0 via a quite fast adapter and it too tops out around 200Mbps for sustained transfers.) That's for a normal harddrive though. You have specified that you are using a "microvault" though, which is a flash drive, not a harddrive. Flash memory is among the slowest types of memory out there and you have to spend quite a fair bit to get the fastest type of flash memory (which is probably capable of coming close to USB 2.0 specs.)

And yes, most modern flash types do read far faster than they write. In some cases, a good 4x faster read versus write even.
 
ddanj said:
how do you know? it says USB 2.0 on it.

Is there a way to verify this? if it IS a USB drive problem, or a computer/driver problem?
Click to expand...

I know cos I am an electronic engineer and its my business to know.
Its also pretty common knowledge that a USB device is unlikely to run at 480mbps.
You have done zero research yourself, ask for answers here, are given them and then dispute them.
Why dont you use google seeing as its you that doesnt know.

You are still going on that there is a problem, you have been told the speed is fine.
Use www.google.com for more info.
 
I don't really want to turn this into a flame war.

I'll just say, thanks for the explanation :)
 
You must log in or register to reply here.
Back
Top