Can someone explain USB3 - USB3 transfer speeds? Something odd!

pfpf

hi,
I've had need to do large amounts of data transfers between portable HD's this week.
I was experiencing such slow, annoying speeds using windows own file transfer system (around 15mb/s) that I did some searching and now use TeraCopy (around 60mb/s).

last night while transferring 300gb or so I noticed an odd thing. btw, these transfers are from one portable HD to another, both plugged into front USB3 sockets.

I was getting my 60ish mb/s transfer speeds via TeraCopy but I opened a movie via VLC player just to have on in the background, I did think this may slow down the transfer rate so was going to shut it down, but instead I saw the transfer rate jump to 93-100mb/s spiking at well over 120mb/s on a regular basis. as soon as I closed VLC the rate dropped back to 60mb/s.

a few more on./off's of the movie got the same result every time.

so whats going on here? why am I transferring at nearly twice the speed while playing a movie? and what could I do to get those high rates without playing a movie, something technical is happening but I don't know what.

thank you.

p.s transferring now as I type again with a movie playing/typing and getting those higher rates.

I_have_spoken

What tool is reporting the transfer rate? It could be adding both reads and writes together and giving a single figure for the drive.

pfpf

thanks.
its just the figure teracopy is showing as the transfer rate of the files being moved(just like windows own transfer window would show a current transfer rate). it also has a countdown timer for how long is left and that halves too.
what should have taken 2 hours to transfer last night(without movie playing) took an hour(with movie playing).
now I don't actually know what speed it should be transferring at, maybe around 100mb/s is actually correct but I am not getting that without playing back the movie. of course other methods may be used to reach a higher rate, its just the playing the movie method is what I stumbled on last night.

p.s currently speeding along at 112mb/s+ with movie playing. dropping to 60mb/s when I stop movie.

paddyrg

Perhaps watching the video on VLC is taking priority from other tasks that might be going on in the background? Mysterious.

pfpf

thank you.
this is weird and is the type of thing that will annoy me till I know for sure.

I have now found that opening VLC player is enough to boost the transfer speed, I don't actually have to play a movie.

I am happy to open VLC to gain the speed increase but as you suggest, something must be taking priority over my transfer speed that VLC removes.

how to find the culprit/s?

pfpf

out of interest what are others real world transfer speeds using USB3 devices?

pfpf

damn, I have to go out now just as I was sleuthing.

I have randomly opened other programmes on my PC, some make no difference but others result in the same increase in transfer speed that VLC delivers.

psychic_teabag

Is it a laptop or a desktop ? I wonder if starting up VLC moves the system as a whole from some sort of lower-power state to higher power. eg increasing a clock rate, or maybe even enabling a second cpu or core. laptops might have more aggressive power-saving. May depend on whether it's charging or running from battery.

If you haven't already, you could fire up task mgr to see if it reports any interesting changes in the two modes. (Does windows still have perfmon - that would be another option if it's still around.)

Other experiments could be to see the rate when copying from one external disk to internal disk, and/or from internal disk to external disk.

kwikbreaks

I think the OP probably has a desktop as he mentioned front usb3 ports.
I was interested by this so tried it on my desktop.
I have no usb3 ports at the front and run a powered hub from a rear usb3 port.

Transfers from a mechanical internal drive to a portable USB3 drive run at ~ 100MBps and between two portable drives on the same hub go at 90-95MBps according to Teracopy figure. I retried with some different files from portable to internal and they were slower at ~ 70MBps - I'm guessing position on platter was the reason for that or it may just have been the change of transfer direction. These were all large movie size files.

Playing around with VLC on source target and other drive occasionally slowed things but never gave a consistent boost.

The Teracopy speed figure compares well with the W10 performance monitor figure (I'm guessing they both use the same Windows metric anyway). The reported speeds tied in well with reported file sizes and times.

So - I have no clue whatsoever why the OP gets the speed boost.

pfpf

its a PC.
thanks for the input guys.

I don't know much about task manager but processes shows:
teracopy using 0-10% cpu when running alone, using 7-15% cpu when VLC is launched. the numbers fluctuate.
nothing else appears to change.

just to reminder, without teracopy at all I was only getting 15mb/s using windows 7 own file transfer system which is why I originally went on the search and found teracopy, which gave me the roughly 60mb/s. then a boost to around 100mb/s when launching VLC or selected other programmes.

confused, but I will try out other scenarios and see what happens.

paddyrg

Ultimately, computers are far too complex to ever work let alone exist (as anyone with an understanding of elections in infinite potential wells and other crazy models used to make even the simplest transistor), let alone be as robust as they are! Your circumstances could be down to so many things likely you'll never actually find out.

One other thought, ports on a front panel are effectively a hub from the mobo, and maybe enter a different power state, or get more bus attention, when VLC starts.

Or maybe the copying software misinterprets the data rate when VLC is open and the drive is spinning data off the pattern at the same time. You could try timing the same file a few times instead of trusting the software to tell you accurately. It may be the same, it may be an artifact of the way the software uses multiple channels/threads to do the copy and combines figures.

We forget just how complicated these systems really are sometimes!