Peter said:
Win7 SP1
When so copying the transfer rate varies
constantly. The dialogue box gives a time of
copying from 1 to 6 hours. Is this because some
files are difficult to copy?
Peter
USB flash drives have low seek time (1 millisecond).
There should not be quite as much variation, as you get
when transferring file-by-file using rotating hard drives.
Those have a significant seek time.
Flash drives slow down a bit, if block substitutions
are needed. (You've got some bad flash cells.)
Check the reviews for your two flash drives. See
if there is known variation in one or both of them.
*******
An SSD drive on the SATA bus, it has a seek time
of about 1/10th that of USB2. The reason for that,
is USB2 uses a polling method, and part of the time
is related to how the bus works. SATA is point-to-point and
not shared, so you're getting closer to the characteristics
of the flash chips themselves.
The lowest seek time, is for RAMDisks (a box holding a
bunch of memory DIMMs). Those can be connected to a
motherboard bus, and have latencies as low as 0.002 milliseconds.
Or about 500 times faster at it, than a USB2 flash drive seek.
Paul