• Comments 7
  • Likes

Virtualization Nation,

Last week, I blogged about the importance of HA for unplanned host downtime. By the number of responses, this is clearly a hot topic. Today, I was going to discuss planned downtime, specifically, the differences between Quick Migration and Live Migration; however, after sifting through all that feedback last week I realized that we need to dispel some myths first...

After my last blog I received almost two dozen email telling me that VMotion was far superior for unplanned host downtime and that it was a much better HA solution because it could live migrate virtual machines. I’ve heard this fallacy espoused for many years and, folks, this simply isn’t the case.

In the case of unplanned downtime, VMotion can’t live migrate because there is no warning. Instead you must have VMware HA configured and the best it can do is restart the affected virtual machines on other nodes which is the same as what is provided with Windows Server 2008 Hyper-V and Failover Clustering.

Here are a couple of quotes from VMware’s own document, Automating High Availability (HA) Services with VMware HA.

Page 1 paragraph 2 states:

Using VMware HA, virtual machines are automatically restarted in the event of hardware failure…

Page 8 states:

How does VMware HA work?

VMware HA continuously monitors all ESX Server hosts in a cluster and detects failures. An agent placed on each host maintains a “heartbeat” with the other hosts in the cluster and loss of a heartbeat with the other hosts in the cluster and loss of a heartbeat initiates the process of restarting all affected virtual machines on other hosts.

HA monitors whether sufficient resources are available in the cluster at all times in order to be able to restart virtual machines on different physical host machines in the event of host failure.

The point being VMware HA and Hyper-V with failover clustering accomplish the same thing: virtual machines are RESTARTED on another node. No better, no worse. If you still don’t believe me, find one of your ESX Servers and go pull out the power plug. (Just don’t say I didn’t warn you.)

Cheers, -Jeff

Your comment has been posted.   Close
Thank you, your comment requires moderation so it may take a while to appear.   Close
Leave a Comment
  • Virtualization Nation, Last week, I blogged about the importance of HA for unplanned host downtime. By

  • Un veloce post per segnalarvi che anche Jeff Woolsey (Senior Program Manager del team che sviluppa Hyper-V

  • There have been a lot of back and forth disucssions around "comparing" VMware's HA/VMotion and Microsoft's Quick Migration features. Recently, VMware distributed a blog post around it as well as a video on Blip.tv. Quick migration in the release candidate

  • We're two dates into our roadshow and I've twice been asked to do a comparison of VMware and Microsoft

  • I've been talking at a number of Windows 2008 customer launch meetings over the last few weeks and I

  • Hi,

    I thought I will put an update to this post. Hyper-V Live migration which will be released with the next version of Hyper-V is almost here. Even check out the videos at http://www.virtualizationteam.com/microsoft/hyper-v/videos-on-the-new-version-of-hyper-v-and-hyper-v-server.html to see Hyper-V Live migration in action.



  • Since we are comparing Live Migration with VMWare's vMotion, anyone thinking of implementing one of these two environments should be aware of VMWare's "Fault Tolerance" feature which can instantly have a machine running on a second host in the case of "unplanned downtime". No restarting required. Read more here: http://www.vmware.com/products/fault-tolerance/