On May 27, 2018, Paul wrote
(in article ):

Scott wrote:
Two different USB sticks, both 16GB and both formatted NTFS. One
writes about three or four times as fast as the other, using the same
files. Any ideas? Could this mean the very slow one is on its way
out, and is there a way of testing it?

Thanks

If they're "different", they could have a different Flash
chip or chips, plus a different controller.

On the USB3 sticks, even a cheesy USB flash key can manage
100MB/sec on reads. But there is a great variation on writes.
Some will only do 10MB/sec on write or 20MB/sec on write.

There are a few sticks that get closer to symmetric. Maybe
you get 200MB/sec on read, and 150MB/sec on write or so.

This means you have to shop around, if that kind of speed
is important to you.

If you use Newegg or Amazon, sometimes the spec isn't available,
but a customer review will list the tested HDTune read and
write performance, and "that's your spec". That's how you
shop for a good one.

I haven't checked on these lately, and this is what I found now.

https://www.newegg.com/Product/Produ...9SIA12K5W43170

SanDisk 128GB Extreme Pro $79
read "up to" 420MB/s
write "up to" 380MB/s

And that means, after a few months it will probably
be writing at 200MB/sec or so :-) The read will be
a bit more consistent, and maybe hit 350MB/sec. It
depends on how much sparing the stick has to do,
to spare out bad sectors, as to some of the speed
drop. On reads, you have to wait for error correction,
if the sector is severely errored. And there's
a real good chance there are TLC chips in there.
Don't get too attached to the stick, because
it won't last forever.

USB3 performance at the high end, is sensitive to the
motherboard chip. An Intel or AMD Southbridge can get
closer to the true USB3 speeds, because the Southbridge
has a high bandwidth path to the target. Some add-on
chips, the bus connection is PCIe x1, but the bus
standard might be a slower one that runs USB3 at
half-rate. Even if the above stick was working
properly, it would only read at slight less
than 200MB/sec on my current (slow) desktop.
On the other machine, I might get 260MB/sec.
I don't have an Intel Southbridge with USB3 on it.
One of those would get closer to the 420MB/sec number
(on the first day).

I don't consider the "read 100 write 10" kind to really
be USB3 sticks, because of the abysmal write rate.

If you go to Walmart, their solution to the problem
is to only sell USB2 sticks :-/ Clever. That's what
I see on the shelf here.

Paul

That was $78 for 128 GBs of Flash. For $150 approx. YMMV you could buy a
Samsung T5 500 GB SSD which used USB 3.1 via a USC-C connection to the
device. They give standard USB-A and Type-C cables. It is super fast and has
a low dollar / GB cost.

--
Peter Kozlov