Abysmal transfer speeds on gigabit network
- by Vegard Larsen
I am having trouble getting my Gigabit network to work properly between my desktop computer and my Windows Home Server. When copying files to my server (connected through my switch), I am seeing file transfer speeds of below 10MB/s, sometimes even below 1MB/s.
The machine configurations are:
Desktop
Intel Core 2 Quad Q6600
Windows 7 Ultimate x64
2x WD Green 1TB drives in striped RAID
4GB RAM
AB9 QuadGT motherboard
Realtek RTL8810SC network adapter
Windows Home Server
AMD Athlon 64 X2
4GB RAM
6x WD Green 1,5TB drives in storage pool
Gigabyte GA-MA78GM-S2H motherboard
Realtek 8111C network adapter
Switch
dLink Green DGS-1008D 8-port
Both machines report being connected at 1Gbps. The switch lights up with green lights for those two ports, indicating 1Gbps.
When connecting the machines through the switch, I am seeing insanely low speeds from WHS to the desktop measured with iperf: 10Kbits/sec (WHS is running iperf -c, desktop is iperf -s). Using iperf the other way (WHS is iperf -s, desktop iperf -c) speeds are also bad (~20Mbits/sec).
Connecting the machines directly with a patch cable, I see much higher speeds when connecting from desktop to WHS (~300 Mbits/sec), but still around 10Kbits/sec when connecting from WHS to the desktop. File transfer speeds are also much quicker (both directions).
Log from desktop for iperf connection from WHS (through switch):
C:\temp>iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[248] local 192.168.1.32 port 5001 connected with 192.168.1.20 port 3227
[ ID] Interval Transfer Bandwidth
[248] 0.0-18.5 sec 24.0 KBytes 10.6 Kbits/sec
Log from desktop for iperf connection to WHS (through switch):
C:\temp>iperf -c 192.168.1.20
------------------------------------------------------------
Client connecting to 192.168.1.20, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[148] local 192.168.1.32 port 57012 connected with 192.168.1.20 port 5001
[ ID] Interval Transfer Bandwidth
[148] 0.0-10.3 sec 28.5 MBytes 23.3 Mbits/sec
What is going on here?
Unfortunately I don't have any other gigabit-capable devices to try with.
