There is question about network between different server,but i got a different situation.
I have two VM in a server,and I tried to test maximum network speed between two VM.
OS : CentOS
VSwitch speed : 10Gb/s (1.25GB/s)
Virtual network adapter speed : 10Gb/s
VM used VSwitch and Virtual network adapter to communicate,and there is no ethernet cable to impact network speed.
VM A : nc -l 20000 > /dev/null VM B : time dd if=/dev/zero bs=100M count=200 | nc <VM A> 20000
200+0 records in 200+0 records out 20971520000 bytes (21 GB) copied, 122.466 s, 171 MB/s
The above command is used to test only network speed(not include disk read and write)
There may some communicate overhead in network.
I thought the network speed should be 1 GB/s,but why the speed is so slow.
What factor impacts the network speed or how can i speedup my network?
Thanks in advanced.
Kindly can you confirm if the type of this Virtual network adapter is VMXNET3 instead of E1000E.
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[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 14.3 GBytes 12.3 Gbits/sec
i user iperf i got 12.3Gb/sec
why it become more than 10 Gb/s speed
and what is different with time dd which i used?
Speed over 10Gb/s is ok, because you run both VMs on single server, so speed depends on your server HW performance and ESXi kernel settings.
About dd...I dont know. Maybe something with netcat.
Let's try to transmit some real data between your VMs and you'll see real (at least sequential) network speed.
When you have vmxnet3 as a Network Device in your VM settings, you also need to install (preferably the latest version of) VMTools too.
To get a VM to work without the tools, there's the E1000 adapter for that, but it is "slower".