USB external Hard drives

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I have a SATA USB external hard drive. The box claims spees of
400mb/s. I have never achieved this - using USB 2 port, I never go
above 40/50Mb/s

Why is this please?
 
Welcome to real life.

But, more seriously, first, do you have your b's and B's straight? Second,
400 Mb/Sec is the max transfer rate of USB 2.0. What do you think your
chances are of achieving the theoretical maximum transfer rate of anything?

Good luck,

Mike
 
I have a SATA USB external hard drive. The box claims spees of
400mb/s. I have never achieved this - using USB 2 port, I never go
above 40/50Mb/s

Why is this please?
Click to expand...

Does the box claim 400Mb/s or "up to" that?
400Mb/s is only the USB theoretical maxium bus speed, not
the speed of the drive or the resultant realized speed. In
other words, marketing departments are twisting the truth to
make products seem better than they are, and feel they can
get away with it because it is very common for products to
be vaguely rated this way, other manufacturers also do this
with some USB2 external products.

Also note the difference between "Mb" (megabit) and "MB"
(megabyte). 8 bit = 1 byte, 400Mb = 50MB

Also, it is very unlikely you actually achieve 40-50MB at
all, except in extremely limited, cached transfers. Typical
USB2 speed is about 35MB/s or less depending on the size &
number of files (much slower with many tiny files).
 
Also note the difference between "Mb" (megabit) and "MB"
(megabyte). 8 bit = 1 byte, 400Mb = 50MB

Also, it is very unlikely you actually achieve 40-50MB at
all, except in extremely limited, cached transfers. Typical
USB2 speed is about 35MB/s or less depending on the size &
number of files (much slower with many tiny files).
Click to expand...

Thanks! Makes sense now.
 
Its a fairly common marketing trick to quote that Max USB2 speed & imply
the drive works at that speed.
In the reviews etc. I have seen for USB2 7200rpm Hard Drives the tests show
the actual
speed as almost exactly a half of that for a standard modern 7200rpm HD
internal mounted.
Mouse
@@@
 
Thanks! Makes sense now.
Click to expand...

I should also clarify that the theoretical max for USB2 is
sometimes (and even more theoretically) claimed as 480Mb/s
instead of 400 as that is the largest rate one could
mathematically produce. It may be possible some very short
cached transfer from the HDD cache to the system over USB2
could be at 400Mb/s but it would be so brief to be trivia
instead of a parameter one could use to decide whether it
had a suitable throughput for any particular use.
 
I have a SATA USB external hard drive. The box claims spees of
400mb/s. I have never achieved this - using USB 2 port, I never go
above 40/50Mb/s
Click to expand...

Megabits and Megabytes perhaps?????
 
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