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
