Understanding how VMware VMotion live migration works

VMware's VMotion live migration is one of the most sought-after features of vSphere. An expert explains how VMotion works and its significance.

VMware Inc.'s VMotion feature performs live migration, which enables the movement of running virtual machines (VMs)...

from one physical ESX host to another. VMotion is one of the most sought-after and powerful capabilities in VMware vSphere because it enables so many critical infrastructure features while creating zero downtime for end users.

How VMotion works and capabilities

  • Load balancing: VMware's Distributed Resource Scheduler (DRS), you can load-balance virtual infrastructure resources between ESX servers. If one of the hosts nears overutilization, guest VMs can be migrated from one ESX Server to another while in use by end users (using VMotion).
  • Distributed Power Management (DPM): moves running VMs from one ESX server to another using VMotion so that ESX Servers can be powered off when the load on the virtual infrastructure is low. This can tremendously reduce a company's power and cooling costs.
  • Maintenance of ESX servers: with VMotion, VMware administrators can move running virtual machines off one ESX server to another to perform hardware or software maintenance, software patches and so on ESX hosts. In fact, VMware's Update Manager (VUM) uses VMotion to apply patches.

VMware's VMotion is offered in three of the six vSphere editions: Advanced, Enterprise and Enterprise Plus. Additionally VMware's vCenter is required.

Until recently, VMware had no competitors that offered anything similar to VMotion. With the release of Microsoft's Windows 2008 R2, Microsoft now has a similar feature to offer called "live migration."

As of September 2009, long-distance VMotion is officially supported by VMware but a tremendous amount of hardware and bandwidth are required to make this work. See Joep Piscaer's post on long-distance VMotion (TA3105) to learn the requirements and details.

For more information on VMotion go toVMware's VMotion product page.

Return to guide's main page for more on VMware virtualization products and features .

About the author
David Davis is the director of infrastructure at TrainSignal.com -- the global leader in video training for IT pros. He has several certifications including vExpert, VMware Certified Profession (or VCP), CISSP, and CCIE #9369. Additionally, Davis has authored hundreds of articles and six video training courses at Train Signal, where one of the most popular course is the VMware vSphere 4 video training course. His website is VMwareVideos.com. You can follow Davis on Twitter or connect with him at David on LinkedIn.

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