slow network transfer speeds

[bwana]

2 pcs connected by cat 6 cable an gigabit switch (cable runs 20 feet, new netgear switch)
(opteron @3 ghz,2 gig ram, gigabit NIC on mobo, windows 7 pro 32 bit)
(core i7 920 @ 4ghz, 6 gig ram, gigabit NIC on mobo, windows 7 pro 64 bit)

8 gig file transferred from one pc to another.
Transfer starts out strong an peters out to 1.5 megabytes/s.

Removed remote differential compression on both machines.
Disabled autotuning on both machines.

Transfer starts out much stronger (~100% network utilization!) but then peters out to 3 MBs/s

It wants an hour to transfer an 8 gig file! Shouldnt this transfer be faster? How can I diagnose the problem?

iperf shows 503 Mbits/sec with an 8 k window size and transferred 601 MBytes. shouldnt this be closer to 900 Mbits/s?

well, setting the tcp buffer to 65000 gets me to 98%utilization so it seems that if i want my transfers over the LAN faster I need to manually make the window bigger every time I drag a big file from one box to the other. but for internet stuff, that window is too big. is there a way to make the buffer bigger for LAN only transfers?

 

[Jeroen1000]

First the disclaimer that I am by no means an authority on the subject.

First of all, your Iperf results appear to be pretty normal. I get similar results with an 8k window. Bumping the window size to 64k or larger does the trick nicely. This should indicate your transfer path/cables are sound.
Just to rule out any transmission errors, you could do a netstat -e (on the command prompt)

Using bigger buffers should make transfers go faster, however, since your speed is only 3 MB/s I wouldn't take that route. Obviously there is more going on than that.

First thing I would try is using FTP. Download Filezilla server and client and transfer away. Second thing I would do is check my nic's drivers. Often, windows 7 recognizes your nic out of the box and gets the real vendor driver from a Windows update. Check the vendor's site though, as that assures you of having the latest driver.

Let us know how your tests pan out


ps: Your switch may be fried too. It is a managed or a standard? IF it is possible, you could always connect the 2 computers directly, or try another switch if you have one. You can use any straight cate5e (or above) cable to connect 2 computers if they both have gigabit nic's.

 

[bwana]

filezilla was a lot of work to set up and i dont like the idea of running an ftp server just to transfer a couple of video files once a week. but i did it just to test it out. filezilla was no better- (. But maybe i dont know how to set it up. In the setup it asked to use some random port (14127?) but ftp is supposed to be port21. Anyway that random port doesnt work, but 21 does.

the switch is a netgear 605-brand new.plain vanilla unmanaged.
both pcs report a 1 gigabit connection.
I'll update the nic drivers and see what that does.

I still cant get over how iperf does so much better than drag and drop in windows.-iperf shows 50% network utilization with an 8k window. A windows drag and drop shows ~8%. Iperf shows a sustained netork utilization. Windows gives me this sawtooth pattern that oscillates between 0 and 8%.

 

[Jeroen1000]

filezilla was a lot of work to set up and i dont like the idea of running an ftp server just to transfer a couple of video files once a week. but i did it just to test it out. filezilla was no better- (. But maybe i dont know how to set it up. In the setup it asked to use some random port (14127?) but ftp is supposed to be port21. Anyway that random port doesnt work, but 21 does.

I'm guessing that random port is to manage the server. Took me about 10 minutes to install the server and client and use it for testing. Don't really know but it sounds you were making it hard on yourself. Also, there is a big chance you are behind at NAT gateway. No one from the outside will be able to contact your FTP-server unless you map the correct ports to the correct LAN-ip.

I still cant get over how iperf does so much better than drag and drop in windows.-iperf shows 50% network utilization with an 8k window. A windows drag and drop shows ~8%. Iperf shows a sustained netork utilization. Windows gives me this sawtooth pattern that oscillates between 0 and 8%.

Iperf tests raw speed, without the protocol overhead of CIFS/samba. It's a test of your theoretical maximum speed. I even believe it does not use the HD. So that are two big limiting factors it rules out.

What is your Iperf speed with a 64k window? It should be well above 500 megabit. Preferably around 800 or more (run multiple tests). I am actually out of ideas here. Try to turn off all anti-virus, anti-spyware and everything that might interfere with file transfers. Update Windows, make sure you HD isn't busy defragmenting or such. If Iperf with a 64k window yields a strong speed, it might just be a OS/driver setting or some software that's interfering...

 

[tipstir]

2 pcs connected by cat 6 cable an gigabit switch (cable runs 20 feet, new netgear switch)
(opteron @3 ghz,2 gig ram, gigabit NIC on mobo, windows 7 pro 32 bit)
(core i7 920 @ 4ghz, 6 gig ram, gigabit NIC on mobo, windows 7 pro 64 bit)

8 gig file transferred from one pc to another.
Transfer starts out strong an peters out to 1.5 megabytes/s.

Removed remote differential compression on both machines.
Disabled autotuning on both machines.

Transfer starts out much stronger (~100% network utilization!) but then peters out to 3 MBs/s

It wants an hour to transfer an 8 gig file! Shouldnt this transfer be faster? How can I diagnose the problem?

iperf shows 503 Mbits/sec with an 8 k window size and transferred 601 MBytes. shouldnt this be closer to 900 Mbits/s?

well, setting the tcp buffer to 65000 gets me to 98%utilization so it seems that if i want my transfers over the LAN faster I need to manually make the window bigger every time I drag a big file from one box to the other. but for internet stuff, that window is too big. is there a way to make the buffer bigger for LAN only transfers?

NIC
Onboard (PCI or PCI-E)
PCI
PCI-E

PCI-E is faster than PCI, but you can get good speeds with PCI. There is a program called Tera-copy that uses the RAM as a buffer to copy files. Windows 7 has this feature too. If you don't see the transfer speeds then you need to tweak the system more. TCP Optimizer or Dr TCP might be your better bet. Don't want to go over kill in tweaking. This means all PC's that need to transfer files would need to be tweaked!