USB card reader problem

[Tony Baechler]

On 8/17/2015 2:10 AM, J.Witvliet at mindef.nl wrote:
> I've likewise behaviour: copying (or rsyncing) goes too fast, obviously buffering.
> When umounting, or doing the sync command, you'll get the expected delay.
>
> One can avoid that, by adding the "-o sync"option when mounting.
> Then copying itself will be slow ;-)


Yes, I know, but that's not my problem.  Even with dd, as you can see from 
my typescript, sometimes it's really slow but not always.  I am not sure if 
it's a kernel issue or a hardware problem.  Why would it sometimes copy at 1 
MBPS and other times 19 MBPS?  Similarly, why, when it's really slow, does 
it take 2M41S to unmount but when it's fast, a fraction of the time even 
though I copied more data?  More to the point, why do I get the strange 
kernel error about not being able to enumerate device on port X?