I just finished some informal testing of several jump drives, and it
raised some questions. Perhaps someone here can explain this...

I tested 2 drives on opposite ends of the advertised speed spectrum - 
one said 30MB/s read, 20 MB/s write (assuming the PC can do that) and
was expensive, and the other was a 2 GB unit store brand for $15. No
speed rating and the absolute cheapest I could find. Available by the
handful in a barrel! Both were mounted in the same port on the same PC,
with write caching turned off.

With a read/seek/write test utility, they both showed 8.5MB/s writes for
5MB worth of data. This may be a limitation of the speed of the host PC,
but not bad.

An extended, 2GB write, slowed to 1MB/s on the first drive near the end,
while the cheap one dropped to 200kB/s toward the end. The fast one took
about 15-20 minutes to fill, the second took almost 2 hours. The first
is reasonable to use real time, the second isn't.

Considering there is no physical seek time, what would cause the speeds
to drop so much over the full transfer? Why can't the speed be maintained?

BTW, in comparison with a real hard drive, the port itself doesn't seem
to slow down and the real drive maintains transfer rate, so that should
rule out any PC buffering problem, at least to this big of a degree.

Any ideas?

-Skip

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