Slooooow USB key speeds

[Robin Laing]

Kanwar Ranbir Sandhu wrote:
> On Sun, 2009-02-01 at 18:14 -0500, Kanwar Ranbir Sandhu wrote:
> 
>> I'm starting to think something is not quite right with the USB key (or
>> in the way it's being detected): I tested transferring files to my PSP,
>> but didn't see any of the same speed issues. I was able to copy large
>> files back and forth without any problems.
> 
> More testing with my PSP and the USB stick has revealed large file
> transfers (e.g. 1 GB in size or more) destroy the transfer speed.
> Transfers start up fast (around 20 MBps), and after a few seconds begin
> to drop.
> 
> The difference being the Kingston USB stick drops to 1 MBps or less,
> whereas the PSP is able to maintain a speed of around 6.5 MBps.  Both
> devices connect at hi-speed (480 Mbps).
> 
> Anyone know what's going on?
> 
> Regards,
> 
> Ranbir
> 

Different standards and quality.

I have dealt with this in the past with Coursair sticks.  Work great in 
Windows but some of them wouldn't mount normally in Linux.  We have 
moved from Corsair to Xporter USB sticks.  No issues that I have seen yet.

As others have said, the controllers on the chips may have some 
buffering and able to put data out at a high speed to start but then max 
out.  Remember that the standard is for maximum speed, not sustained 
speeds.  Each USB stick has a controller that can reach it's maximum 
speed quite quickly.  Also, some manufacturers have their "High Speed" 
sticks at a premium price.



-- 
Robin Laing