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Contrary to what some virtualization vendors have said, zero-downtime migration is a business-critical feature that can completely change your IT processes and enable completely new capabilities — look at DRS and the new Distributed Power Management.

VMware’s VMotion is also rock solid. Richard Garsthagen recently released a little demo app called VMJuggler that demonstrates this nicely for folks that haven’t seen it in action. Richard wrote it for Barcelona TechEd, where he wanted to "show the Microsoft minded crowd that running Microsoft Windows
applications in (VMware) virtual machines works fast, stable and
manageable." Link: VMjuggler: 5 Days of TechED, 10.000 vMotions later….

For the show I created a Windows 2003 64 bit virtual machine and
installed Microsoft SQL 2005 in it. This virtual machine was placed
together with some 100 other virtual machines on our 6 server ESX
environment. I then hit the SQL server with DBhammer to simulate on
average 150 sql clients accessing the database, doing around 1.200
queries a second.

We wanted to show the audience that a
Server like this, can be moved around physical boxes (using VMotion),
without any downtime of the SQL server, so I wrote a small application
called the VMjuggler. This application would initiate a live migration
of my Virtual SQL server every 10 seconds to another physical server.
The VMotion process itself took around 10 seconds, then waited 10
seconds to be moved again. After the 5 days the SQL virtual machine
hopped server more then 10.000 times, with out issues what so ever…

Richard has said he will give a small prize to the first person who wastes enough time generates a million VMotions with VMjuggler. But I actually thought Richard’s comment toward the end was the most interesting.  VMotion has been out since 2003 and old news to anyone already using VMware, but with a virtual machine ping-ponging away in the background at a conference, you quickly get over the ‘gee whiz’ aspect of the technology — yes, it’s cool and it’s real — and can now get to the real question — how is this going to benefit me? Or as Richard says:

Running this demo really allowed us to explain to our visitors that
VMware is more then just a hypervisor company, actually most of the
software we develop is about solving ordinary IT problems like data
protection, resource management, availability, security, provisioning,
etc, we just like to use the virtualized architecture to create these
solutions.