Testing SMB Live Migration on WS2012 R2 Hyper-V

Today I got “generation 2” of the lab functioning the way I want it to today.  The hosts are two Dell R420 12th generation servers, with 2 * 6 Core CPUs (24 logical processors each), 64 GB RAM and an extra Chelsio T440 CR quad port iWARP SFP+ NICs (for RDMA/SMB Direct).  The HP DL360 G7’s are now the nodes in my Scale-Out File Server.

2 of the iWARP NICs are used for the vSwitch NIC team.  The other two are not teamed (prevents RDMA) and are on different subnets to support Multichannel to the SOFS.

I have a script that tests the migration of a VM using the different WS2012 R2 options and times the movements.  I just compared TCP/IP Live Migration (over 1 * 10 GbE with some CPU impact) and compared it with SMB Live Migration which used 2 * 10 GbE.  This was done with a single VM with 56 GB of statically assigned RAM.  The results are in:

  • TCP Live Migration: using around 9.8 Gbps took 58 seconds (which is excellent)
  • SMB Live Migration: using nearly all of the available 20 Gbps took 35 seconds

Think about that … a Linux (did I mention that?) VM with 56 GM RAM moved between two hosts in 35 seconds … with no noticeable CPU impact on the hosts caused by Live Migration!

I actually moved 50 VMs concurrently yesterday and there was no noticeable CPU impact!

There was a little engineering required:

  • Jumbo Frames was configured on the NICs and (thanks to Didier Van Hoye, aka @workinghardinit) I verified it end-to-end using ping <IP> –l 8400 –f.  This gave me 10 Gbps on a single NIC.
  • The final piece was to update the driver … the out of box driver refused to use more than 5 Gbps on each NIC via SMB Multichannel, usually sitting at 2.4 Gbps most of the time.  Now I had 20 Gbps.
  • I verified that RDMA was kicking in almost immediately via PerfMon.  Multichannel is kicking in almost immediately too.

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