Low umass performance with USB 2.0 ports

[Eugene Grosbein]

"Eygene A. Ryabinkin" wrote:
> 
>   Good day.
>  I am observing very low umass performance: when I am trying to move a large
> file from/to my USB 2.0 flash that is plugged into the USB 2.0 port: transfer
> starts fine at 3.5 Mb/sec, but after some 20 Mbytes it hangs and the process
> (dd) stay in the wdrain state. The activity LED on the flash shows no activity.
> Operations do continue, but very slow and the most time of the copying process
> spends in the wdrain state. All attempts to invoke `sync` or to see the
> file state via `ls` are hanging until `dd` leaves the wdrain state.
>  It does not matter what flash is used: I tried Apacer and the Kingmax ones --
> the result is the same.
>  If I plug the flash into the USB 1.1 port and trying to move some data -- it
> works fine, no hangs. Speed is 500 Kb/sec.

What is filesystem has your USB drive?
FreeBSD 4.x had very low performance with FAT filesystem,
writing process spent lots of time in the wdrain state too.

Eugene