I have a network consisting of about 40 Windows 7 machines (physical) and 2 servers (Virtual, ESX) which are Server 2008 Std ed (one is a SBS 2008 but they're the same 'under the hood'). Network is a gigabit.

It appears I am having some issues w/ performance on the Server 2008 boxes. Running a test from a Windows 7 machine which is connected to the same LAN, iPerf reports good speed results (90+ MB/s) from the Win7 -> Server2008 end, but VERY slow speeds (4 MB/s) from the Server2008 -> Win7 End.

Admittely, when copying files (to and from the Server 2008 VMs) there are slow downs but they're certainly faster than the speeds iPerf is reporting. I'm somewhat lost as to why this is the case, so I thought trying to nail down why iPerf is reporting slow speeds when running a test from the server to the Windows 7 clients would be a good place to start.

At first I thought the issue may be with the ESXi config so I spun up a brand new Windows 7 VM on the same hypervisor that houses the two Server 2008 VMs but the Windows 7 VM did not exhibit this behaviour -- when I test it from a physical Win 7 box, the Win 7 VM gets 90+ MB/s both directions. So -- Win 7 seems to be fine, but both the Server 2008 VMs I've got are exhibiting this issue. I've installed latest patches on these servers. They're using the Intel E1000 NIC (not the VMXNET3), but so is the test Win 7 VM.

Any ideas on why this may be happening?

Here are the test results run from a Win7 Machine to the Server 2008 VM:

    iperf.exe -c 10.1.1.1 -r -P 1 -i 1 -p 5001 -w 64.0K -f M
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 0.06 MByte
------------------------------------------------------------
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 0.06 MByte
------------------------------------------------------------
[  4] local 10.1.1.24 port 51010 connected with 10.1.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  4]  0.0- 1.0 sec  75.4 MBytes  75.4 MBytes/sec
[  4]  1.0- 2.0 sec  84.0 MBytes  84.0 MBytes/sec
[  4]  2.0- 3.0 sec  84.6 MBytes  84.6 MBytes/sec
[  4]  3.0- 4.0 sec  89.5 MBytes  89.5 MBytes/sec
[  4]  4.0- 5.0 sec  87.2 MBytes  87.2 MBytes/sec
[  4]  5.0- 6.0 sec  88.6 MBytes  88.6 MBytes/sec
[  4]  6.0- 7.0 sec  85.0 MBytes  85.0 MBytes/sec
[  4]  7.0- 8.0 sec  81.6 MBytes  81.6 MBytes/sec
[  4]  8.0- 9.0 sec  69.5 MBytes  69.5 MBytes/sec
[  4]  9.0-10.0 sec  89.1 MBytes  89.1 MBytes/sec
[  4]  0.0-10.0 sec   835 MBytes  83.4 MBytes/sec
[  4] local 10.1.1.24 port 5001 connected with 10.1.1.1 port 58849
[  4]  0.0- 1.0 sec  1.38 MBytes  1.38 MBytes/sec
[  4]  1.0- 2.0 sec  2.31 MBytes  2.31 MBytes/sec
[  4]  2.0- 3.0 sec  9.06 MBytes  9.06 MBytes/sec
[  4]  3.0- 4.0 sec  8.38 MBytes  8.38 MBytes/sec
[  4]  4.0- 5.0 sec  7.00 MBytes  7.00 MBytes/sec
[  4]  5.0- 6.0 sec  2.44 MBytes  2.44 MBytes/sec
[  4]  6.0- 7.0 sec  1.69 MBytes  1.69 MBytes/sec
[  4]  7.0- 8.0 sec  4.81 MBytes  4.81 MBytes/sec
[  4]  8.0- 9.0 sec  3.75 MBytes  3.75 MBytes/sec
[  4]  9.0-10.0 sec  5.19 MBytes  5.19 MBytes/sec
[  4]  0.0-10.4 sec  46.2 MBytes  4.45 MBytes/sec

Here's a test run from the same Win 7 machine to the Win 7 VM which is on the same hypervisor:

iperf.exe -c 10.1.1.197 -r -P 1 -i 1 -p 5001 -w 64.0K -f M

------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 0.06 MByte
------------------------------------------------------------
------------------------------------------------------------
Client connecting to 10.1.1.197, TCP port 5001
TCP window size: 0.06 MByte
------------------------------------------------------------
[  4] local 10.1.1.24 port 50876 connected with 10.1.1.197 port 5001
[ ID] Interval       Transfer     Bandwidth
[  4]  0.0- 1.0 sec  81.6 MBytes  81.6 MBytes/sec
[  4]  1.0- 2.0 sec  90.8 MBytes  90.8 MBytes/sec
[  4]  2.0- 3.0 sec   100 MBytes   100 MBytes/sec
[  4]  3.0- 4.0 sec  87.0 MBytes  87.0 MBytes/sec
[  4]  4.0- 5.0 sec  93.4 MBytes  93.4 MBytes/sec
[  4]  5.0- 6.0 sec  88.1 MBytes  88.1 MBytes/sec
[  4]  6.0- 7.0 sec  89.0 MBytes  89.0 MBytes/sec
[  4]  7.0- 8.0 sec  99.1 MBytes  99.1 MBytes/sec
[  4]  8.0- 9.0 sec  87.5 MBytes  87.5 MBytes/sec
[  4]  9.0-10.0 sec  86.2 MBytes  86.2 MBytes/sec
[  4]  0.0-10.0 sec   903 MBytes  90.3 MBytes/sec
[  4] local 10.1.1.24 port 5001 connected with 10.1.1.197 port 49223
[  4]  0.0- 1.0 sec  72.3 MBytes  72.3 MBytes/sec
[  4]  1.0- 2.0 sec  78.0 MBytes  78.0 MBytes/sec
[  4]  2.0- 3.0 sec  85.0 MBytes  85.0 MBytes/sec
[  4]  3.0- 4.0 sec  90.3 MBytes  90.3 MBytes/sec
[  4]  4.0- 5.0 sec  87.9 MBytes  87.9 MBytes/sec
[  4]  5.0- 6.0 sec  91.1 MBytes  91.1 MBytes/sec
[  4]  6.0- 7.0 sec   106 MBytes   106 MBytes/sec
[  4]  7.0- 8.0 sec   106 MBytes   106 MBytes/sec
[  4]  8.0- 9.0 sec   107 MBytes   107 MBytes/sec
[  4]  9.0-10.0 sec   107 MBytes   107 MBytes/sec
[  4]  0.0-10.0 sec   931 MBytes  92.9 MBytes/sec

I've 'resolved' this issue by conducting an in-place upgrade of the Server to 2008 R2 (up from 2008). Network speeds are saturating the gigabit pipe now.

Your Answer

 

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Not the answer you're looking for? Browse other questions tagged or ask your own question.