Enable compression on Live Migration

One of the cool new features in Windows Server 2012 R2 is the option to make Live Migration faster. Usually when migrating a single vm it is pretty good to see the performance and durance of this migration. But what if we need to patch a Hyper-V Node with 256GB of RAM? Only making the host available for maintenance mode can take up to an hour. Not what we really want to do if we need to wait till a host is ready live migrating all VM’s to other nodes…

There are 2 ways to make Live Migration faster:

  • Live migration with compression:  Here we utilize spare CPU capacity in the host operating system to reduce the amount of data that gets sent as part of the live migration.  In testing this has yielded a 2x to 4x performance improvement without any changes to the virtualization hardware or network configuration.
  • Live migration with RDMA: Here we take advantage of RDMA enabled hardware to deliver amazing performance for live migration, with zero CPU impact.

In this blog I will compare the difference between Default Live migration and the Live Migration with compression.


Below the migration with default migration settings:


You see it took a VM with 6GB RAM about 1:49 minutes to move on 1Gb Network

Now below the results with compression on. You see we made a huge improvement with the live migration:


Happy patching and putting hosts in maintenance mode Smile