VMware or Microsoft? Moving Live Virtual Machines, Same But Different

imageWelcome to the post and today we are going to talk about migrating virtual machines from one host to another.  Before I go any further here is something to get us on the same page:

vMotion and Storage vMotion is to VMware as Live Migration is to Hyper-V

For this post I will be referencing vSphere 5.1, I have not seen any changes with vSphere 5.5.  If there are updates please comment, drop me an email and I will update this post!  I will also be referencing Windows Server 2012, with just a sprinkling of what will come with Windows Server 2012 R2 at the end of the post


Fundamentally the technologies do the same thing they will take running virtual machines from one host to another host with no downtime.  This allows you setup continuously available environments (via clustering), allows you schedule planned maintenance, upgrade of your host environments…etc.  Being able to migrate your virtual environments offers a tremendous amount of flexibly for your datacenter.  Under the covers the process is similar in both as well:

  1. Memory pages are transferred from the source node to the destination node.
  2. Modified pages are transferred.
  3. The storage handle or actual storage is moved from the source server to the destination server.
  4. The virtual machine is brought online on the destination server.
  5. Cleanup occurs.

In regards to migrations I believe that Hyper-V has surpassed VMware from a technical stand point.   The reason I make that statement, is because of some the key differences between the technologies in VMware and Hyper-V.  We will start with simultaneous migrations.

Simultaneous Migrations

vMotion is limited to 8 simultaneous vMotion migrations at a time presuming you have a 10GB Ethernet, it is limited to 4 with a 1 GB connection.  You can learn more about the limitations here: VMware: Limits on Simultaneous Migrations .  This is not new and  if you have been around VMware for any length of time, there has always been a limit on simultaneous Migrations.  With Hyper-V, simultaneous migrations are unlimited.  This allows you to move any amount of virtual machines and storage that you desire.  So if you wanted to migrate a 100 or 1000 Virtual Machines you could.  Now realistically I know not many of you will ever have the need to migrate that many virtual machines however it is nice to know that you will not be limited by Hyper-V.

Shared Nothing Migration

This technology exits in Windows Server 2012 as well as VMware 5.1.  However, Windows Server 2012 was the  pioneer of the technology and I found it is interesting that VMware chose to add it to 5.1.  It is a fantastic feature.  Shared Nothing Migration allows you to migrate running virtual machines from one host to another with no shared storage, no cluster requirements, nothing but a 1GB connection between your hosts.  While this not a High availability solution, you will still need clustering for that, it does provide you a viable option for any stand alone hosts.  This provides you an easy way to migrate the virtual machines on those host you may need to decommission or upgrade without first having to setup a cluster to just move the VMs.  Remember this is also included in our FREE Hyper-V server (see next section) You can learn more about Live Migration and Shared Nothing Migration (even how to use this feature with PowerShell) from this article Keith Mayer wrote: Live Migrate Your VMs in One Line of PowerShell - 31 Days of Favorite Features in #WinServ 2012 ( Part 4 of 31 ) 

Licensing Considerations

Lastly, while I consider this a minor point it is worth pointing out.  With VMware you only get vMotion with Essentials plus or higher.  additionally if you want to have Storage vMotion you will need vSphere [UPDATE] Standard or higher.  I am sure most of you are aware of this, and most customers that us VMware typically will have the Enterprise addition.  With Hyper-V all of these features are included in any version of Hyper-V.  So whether you buy Windows Server 2012 Standard, Windows Server 2012 Datacenter or download the free Hyper-V Server.  In fact our free version of Hyper-V is fully functional.  If you want to give them a try for FREE click on one of the following links:

Closing Remarks and R2 Coming Soon

With all that said I know after talking with VMware professionals they will talk with me about performance and speed of the migration.  I do have to give a nod to vMotion in this regards.  While Windows Server 2012 has been closing the gap, we will really close the gap with Windows Server 2012 R2.  VMware does have an edge in the performance department.  However in R2 there a couple of key improvements coming:

  • Compression:   The memory content of the virtual machine that is being migrated is compressed and then copied to the destination server over a TCP/IP connection.  This is the default setting in Hyper-V in Windows Server 2012 R2 Preview.
  • SMB: The memory content of the virtual machine is copied to the destination server over a SMB 3.0 connection.
    • SMB Direct is used when the network adapters on the source and destination servers have Remote Direct Memory Access (RDMA) capabilities enabled.
    • SMB Multichannel automatically detects and uses multiple connections when a proper SMB Multichannel configuration is identified.

You can learn more about some of the Live Migration enhancements in Windows Server 2012 R2 here: Virtual Machine Live Migration Overview.  Windows Server 2012 R2 also has gone into RTM (you can read about that here: Today is the RTM for Windows Server 2012 R2! ) and will GA on Oct. 18 (you read about that here: Save the Date October 18th! Release for Windows 8.1 and Windows Server R2)

If you want to take Windows Server 2012 Hyper-V for a test drive:

I hope you enjoyed this post, and please comment.  If you missed any parts of the series take a look here:

VMware or Microsoft? – The Complete Series