10gb network link does not achieve the best speed

[oliver19]

I have a Dell PowerEdge R740 server with a 10GB NIC and a 10GB Switch, the VM detects the 10 Gb link but when doing speed tests with the iperf tool I don't get a measure of even close to 10 GB, the maximum it can achieve They are 900Mb, please suggest me how I can resolve this situation.
thank you

[Kaganew]

Hi, i have the same problem, i have 3 host with esxi 8.0 and one host qwith vcenter server. 10gb ethernet cards with a cisco 10gb switch and i test with iperf in two VM get the same 900mb. The VM's have the ethernet adapter VMXNET3, the esxi nic's have 10000mbps full.

[maksym007]

Which vSphere version we are discussing? 

What type of switch you have in cluster? vSwitch on each host or dVS? 

[battybishop]

Have you tried setting MTU to 9000 to enable Jumbo Frames?

[Kaganew]

I tried to change MTU to 9000 on vswitch's, same result. 

I try to change to jumbo frames on switch cisco 10gb?

[kastlr]

Hi,

did you check if your network is in a good shape?
esxcli network nic stats get -n vmnicX

Pause frames might be responsible for a lower throughput.
Configuring Flow Control on VMware ESXi and VMware ESX

And of course you should check if your LAN switch isn't the bottleneck, I assume you're not connected via a Cisco Fabric Extender.
To achieve full performance the LAN Switch should have a non-blocking architecture and a NPU shared switch buffer of at least 16 MB.

[Kaganew]

Hi,  its VMware vSphere 8 Essentials Plus Kit for 3 host. 

Vswitch on all host's

[Kaganew]

I test the two nics:

esxcli network nic stats get -n vmnic2
NIC statistics for vmnic2
Packets received: 244698
Packets sent: 25095
Bytes received: 42893114
Bytes sent: 35118082
Receive packets dropped: 0
Transmit packets dropped: 0
Multicast packets received: 112842
Broadcast packets received: 120895
Multicast packets sent: 0
Broadcast packets sent: 35
Total receive errors: 0
Receive length errors: 0
Receive over errors: 0
Receive CRC errors: 0
Receive frame errors: 0
Receive FIFO errors: 0
Receive missed errors: 0
Total transmit errors: 0
Transmit aborted errors: 0
Transmit carrier errors: 0
Transmit FIFO errors: 0
Transmit heartbeat errors: 0
Transmit window errors: 0

esxcli network nic stats get -n vmnic3
NIC statistics for vmnic3
Packets received: 441773
Packets sent: 200452
Bytes received: 183003408
Bytes sent: 75958843
Receive packets dropped: 0
Transmit packets dropped: 0
Multicast packets received: 113260
Broadcast packets received: 121223
Multicast packets sent: 99
Broadcast packets sent: 248
Total receive errors: 0
Receive length errors: 0
Receive over errors: 0
Receive CRC errors: 0
Receive frame errors: 0
Receive FIFO errors: 0
Receive missed errors: 0
Total transmit errors: 0
Transmit aborted errors: 0
Transmit carrier errors: 0
Transmit FIFO errors: 0
Transmit heartbeat errors: 0
Transmit window errors: 0