vRack bandwidth

Connections on the vRack allows you to max out the secondary network adapters connection. The maximum bandwidth would be the lowest port speed where by if we have 2 servers and one server vRack port is 1 Gbps and the 2nd server vRack port is 10Gbps, the bandwidth between the two servers will be 1 Gbps. Naturally if both servers have 10 Gbps vRack ports then they will communicate at the maximum bandwidth.

We can look to test the vRack port via an iperf test to check the bandwidth of the vRack connections. We will have 1 server in the BHS datacenter and another in the RBX datacenter. You can see more information regarding the datacenters here.

The two datacenters are physically apart. Where by BHS is in Canada and RBX is physically in France. We will look to use the iperf command to test the bandwidth between the two servers:

root@mysuperweb.co.uk:~# iperf -c -i1 -P100 | grep SUM

[SUM]  0.0- 1.0 sec   118 MBytes   987 Mbits/sec
[SUM]  1.0- 2.0 sec   124 MBytes  1.04 Gbits/sec
[SUM]  2.0- 3.0 sec   118 MBytes   989 Mbits/sec
[SUM]  3.0- 4.0 sec   113 MBytes   950 Mbits/sec
[SUM]  4.0- 5.0 sec   112 MBytes   937 Mbits/sec
[SUM]  5.0- 6.0 sec   114 MBytes   958 Mbits/sec
[SUM]  6.0- 7.0 sec   110 MBytes   921 Mbits/sec
[SUM]  7.0- 8.0 sec   114 MBytes   960 Mbits/sec
[SUM]  8.0- 9.0 sec   112 MBytes   937 Mbits/sec
[SUM]  0.0-10.4 sec  1.13 GBytes   934 Mbits/sec

As we can see the physical port is 1 Gbps and at one point we are able to achieve the full network capacity however due to network overheads, we can get approximately 934 Mbps to 1 Gbps throughput.