Hello Networking Enthusiasts – Tomorrow, the US will celebrate Thanksgiving and since we’re so close to a holiday we decided to keep this week’s blog fairly simple and answer some common questions and information we’ve seen over the last few months.
If you have follow-up questions you’d like answered (or more details on what’s below), hit us up on Twitter @ Microsoft SDN!
RDMA and HCI
Q. Network traffic from Live Migrations takes valuable CPU cycles from my tenant VMs. How can I reduce the impact of a live migration for tenants, increase the number of live migrations I can perform, and/or increase the speed of the live migrations?
Although not the default option, SMB can be selected as the live migration mechanism. If selected, SMB can use RDMA under the hood (in this context, known as SMBDirect), which avoids the need to process the GB’s (yes, Gigabytes not bits) of network traffic produced from the live migration (e.g VM Memory or VHDX Storage).
RDMA by-passes the host operating system and removes the processing burden of the live migrations. Since host networking is most commonly constrained by host CPU spreading (remember your VMs are competing for access to the same cores processing network traffic), RDMA eases the effect of the live migration on VMs on the same host as they can now continue to focus on the VMs CPU scheduling needs.
The net effect is an increase to the number of live migrations you can perform at once because the CPU is no longer the bottleneck for the network or affecting your tenant VMs.
Software Defined Networking
Networking Diagnosis Tools