In a new head-to-head comparison published by independent technology assessment firm Principled Technologies, VMware vSphere once again trounces challenger Hyper-V by delivering superior speed, performance, and reliability for zero-downtime virtual machine migrations.  Live VM migration is crucial for proactive maintenance on hypervisor hosts and for distributing workloads as demand shifts — optimizing for either performance or power savings.  Once an exclusive feature of the industry-leading vSphere platform, live migration has become yet another casualty of the checkbox war — where a simple “yes” or “no” cannot sufficiently convey vital technological differences.

Microsoft may position Hyper-V Live Migration as good enough, but a side-by-side comparison clearly reveals that an imitation is never as good as the original.  VMware vMotion continues to improve and vSphere 5 enjoys many new enhancements, including support for multiple 10GbE interfaces to increase bandwidth for migration traffic — complementing the well-proven ability to migrate up to 8 VMs at a time.

Hyper-V Live Migration, introduced two years ago after much delay, will evidently remain stagnant for quite some time to come.  In fact, the shipping version of Hyper-V can still only accommodate a single migration at a time — whether a source or a destination.  This leads to the somewhat disingenuous claim that Hyper-V supports up to 8 concurrent Live Migrations per [16-node] cluster!

Principled Technologies conducted migration testing in two different scenarios, providing objectivity to correct the inaccurate claims of parity between the platforms. In the first scenario, one host in a cluster is running 10 VMs and is put into maintenance mode.  Comparing elapsed times to evacuate each hypervisor quantifies migration speed without conjecture.  In the second scenario, a single busy VM is moved from one host to another.  The elapsed time is considered, but more important is the performance impact to the application undergoing migration.

Take a look at the results and see for yourself:

Host Evacuation: Entering Maintenance Mode

Under real-world conditions, VMware vMotion is over five times faster than Live Migration.  When Patch Tuesday rolls around and it’s time to update Windows-based hypervisors, be sure to build plenty of margin into the maintenance window to allow for host evacuations.  What’s amazing about this victory is that although vSphere 5 now supports multiple 10GbE NICs for vMotion traffic, this scenario used just a single interface on each host.

Tier-One Application: Degradation Caused by Migration

A busy database VM is expected to deliver continuously; minimally impacting application performance during migration is a crucial requirement when demanding SLAs must be met.  VMware vMotion cranks out 63 percent more orders than Hyper-V during a 4-minute migration window. In fact, vSphere needed just half a minute to move a very busy 4-vCPU SQL Server VM with 16GB RAM.  The charts below make it clear: vSphere empowers IT architects to virtualize with confidence.

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