Strange network behaviour.

[SDplus]

So, I have a home network based on Gigabit network parts.
The central point has a 24 port switch on entry pro-scale. DHCP is handled by my ASUS Router connected to that.
My four NAS servers is in another room connected to an 8-port Switch of standard better home quality. It's just connected to the 24 port switch.
Then I have a 5-port switch in another room where I have some gaming stuff and newish Laptop.
To that laptop I connected a 3 TB USB3 disk from which two chunks of data would be copied to one of the NAS's.
The first chunk was about 500 GB, and the NAS isn't quick so I knew it would take a while, but I started this before I went to bed on my main computer which is connected directly to the 24-port switch. And I got transfer speeds between 18 GB/s and 28 GB/s averaging about 22 GB/s.
It's kind of what I expected.
Now, this morning I would start to dump another chunk of data, about 1.2 TB. But this time I started the transfer directly from the Laptop where the USB 3 disk is connected.
I get 7-8 GB/s steady.
I have stopped, tried from the main computer and I get the higher speed directly, then back starting the transfer from the laptop again. 7-8 GB/s again.
Through all of this the 3 TB disk is always connected to the same USB 3 port on the Laptop.

If the situation was reversed, I wouldn't be very surprised, but this just seems very odd to me.
The Laptop has Win 8.1, and the main rig has Win 7 Ultimate. But the disk is still never moved from the laptop. It has not restarted or anything.
The NAS is a fairly old Buffalo Terastation 4-disk in RAID5 with 4 2TB disks in it. But that point remains constant here. The strangeness has to happen in the other parts of the network.

Is there any reasonable explanation for this?

 

[Frennzy]

18 GB/s and 28 GB/s averaging about 22 GB/s.

Uh...no. That's physically impossible given the equipment you describe. Check your units.

 

[SDplus]

Well, it should be MB/s... Did I mention I had a monster headache when I wrote that?
Please transform all GB/s to MB/s...

 

[ZPrime]

The laptop is using hardwired Ethernet, correct? Not Wifi?

Assuming it's hardwired, I would suspect some corner-case incompatibility between whatever version of samba runs on the NAS and something in Win8.1's SMB implementation (vs. Win7).

If the laptop isn't hardwired, remember that USB3 can interfere with Wifi, so that could be a large factor, even if the laptop is on 802.11ac (which is theoretically capable of gigabit+ speeds under ideal conditions).

Note that even if you have ethernet plugged in, if the laptop is also connected to wifi, it may still be trying to use the wifi instead of the wired connection for the file transfer. Win8.1 has made it very difficult to find the network binding order / NIC preference order pane. (Network & Sharing Center -> Change adapter settings -> Press ALT key on keyboard -> Advanced menu -> Advanced Settings option -> Re-order your network connections in the list on the "Adapters and Bindings" tab)

 

[breakingnews]

What are your resources looking like on each host when you run the transfers? Cpu, memory, disk space, a/v, etc.?

 

[SDplus]

Well, remember the source drive is never moved from the Laptop at all. The only difference is that I initiate the transfer from another computer.
Yes, the Laptop is hardwired.
The Main PC is i7-3820 with 32 GB ram over 8 sticks. No overclock at the moment.
The Laptop is i7 Haswell (No CPUid CPU code) its quad core running at 3+ GHz and with 16 GB Memory over 2 sticks.
So both cases ends should have no hardware problems. But still. Why does how I start transfer make a difference when all the hardware remains unchanged?

 

[SDplus]

I suppose if Win 8.1's network solutions work well with Win 7, and not with the NAS, and The Win 7 network has no problem with the NAS, then the re-route improvement would make some sense. I will investigate further with more computers I have on other parts of the network... I hope this is not a problem that will carry over to Win 10 later, because even though I can accept that one Laptop has decreased file transfer speed, I will not like all my PC's have that problems later...

I have another identical NAS but with older Firmware and software on it. I will make some comparisons between them too. And another NAS from another manufacturer entirely, and a Windows Server, so I have a lot to test. But for the moment the 1.2 TB transfer is still running on the Laptop... Unfortunately the NAS decided earlier today to do it's monthly RAID maintenance, so right now the speed is even lower for the transfer. But once that transfer and maintenance is done I will do some more testing.

 

[breakingnews]

Pardon my earlier hasty reply, I misinterpreted your notes. I would still suspect any differences like antivirus or o/s, what previous folks said or the connection from laptop to nas (as pc to nas is fine). Perhaps run a copy from usb3 to laptop local disk, any better? Swap pc/laptop connections as a test to see if issue follows? As noted above the smb issues of course a possibility too. What I was considering earlier was a case where on our file server with fobs of resources a copy was slower than from a client machine! Due to antivirus behaviour from server vs. Client iirc).

 

[ZPrime]

SDplus[/url]":2p4cj7qa]
Well, remember the source drive is never moved from the Laptop at all. The only difference is that I initiate the transfer from another computer.

Bolded for emphasis.

If the USB3 drive is on the laptop, and you "initiate the transfer" using Windows Explorer on your desktop, your desktop copies the files from the laptop to itself, and on the fly then copies them back out to the NAS. Windows is not able to initiate a direct machine-to-machine transfer from a 3rd machine, short of using remote control software to do that.

It sounds like something is a "slow point" with the laptop, and by "buffering" the copy through your desktop and the network, that is oddly improving speed. I'd love to know what / why / how though... Looks like you'd need to break out Performance Monitor on the laptop and log the Disk counters for the USB3 drive, along with the network counters, under both of the different copy scenarios.

Again, if the Laptop is running 8.1 and the desktop is only on 7, and the desktop copies quicker, I'd suspect a SMB version incompatibility between the laptop and the NAS. Possibly they can't figure out SMB2 so are falling back to SMB1, which is slower... but when the Win7 machine acts as a buffer between, it is actually capable of speaking SMB2 to the NAS and thus improving throughput (counterintuitive though it might seem).

 

[breakingnews]

ZPrime[/url]":skttvuhl]

SDplus[/url]":skttvuhl]
Well, remember the source drive is never moved from the Laptop at all. The only difference is that I initiate the transfer from another computer.

Bolded for emphasis.

If the USB3 drive is on the laptop, and you "initiate the transfer" using Windows Explorer on your desktop, your desktop copies the files from the laptop to itself, and on the fly then copies them back out to the NAS. Windows is not able to initiate a direct machine-to-machine transfer from a 3rd machine, short of using remote control software to do that.

It sounds like something is a "slow point" with the laptop, and by "buffering" the copy through your desktop and the network, that is oddly improving speed. I'd love to know what / why / how though... Looks like you'd need to break out Performance Monitor on the laptop and log the Disk counters for the USB3 drive, along with the network counters, under both of the different copy scenarios.

Again, if the Laptop is running 8.1 and the desktop is only on 7, and the desktop copies quicker, I'd suspect a SMB version incompatibility between the laptop and the NAS. Possibly they can't figure out SMB2 so are falling back to SMB1, which is slower... but when the Win7 machine acts as a buffer between, it is actually capable of speaking SMB2 to the NAS and thus improving throughput (counterintuitive though it might seem).

Yea, that's what I was getting at, the path from PC to NAS differing from the path from the laptop to the NAS (driven from the PC through the laptop rerouting back to the PC to the NAS for $Reasons).