On Fri, Mar 11, 2011 at 12:47 PM, John Hasler <[email protected]> wrote: > The hardware doesn't go away when you add another layer or two of > complexity by adding VMWare. > > What's baffling, though, is why you need to add an entire virtual > machine and operating system just to run another process.
If only it were as simple as "running another process". Virtualization is popular because operating systems (not just Windows) are actually quite weak at isolation. Shared libraries, permissions, resource allocation, software which requires exclusive use of particular ports, etc. are issues on various POSIX-like systems, as well as Windows. If I have 25 different applications on one box, I have to wait until ALL of them support and have been tested on a particular level of kernel, hardware drivers, shared libraries, file systems, database versions, whatever before I can safely upgrade. That is a major operational problem in a very heterogeneous IT environment (which most corporations have). Right now we have three Windows and six Linux server OS versions in production. Don't get me started on all the variations of the underlying dependencies - vendors all move at their own pace, and you have to stick with what is "officially supported" to keep that maintenance contract. If you write all your own software and your stack is trivially simple and uniform (e.g. twitter), good for you, but some of us live in the real world. Put another way, vritualization's major benefit is the encapsulation of all of an application's needs into a few big files that can be moved around (even while running!) from one piece of hardware to another. You can efficiently snapshot, clone for dev and QA environments, set up virtual isolated networks, etc. The virtual machine is the "process" unit. It sounds inefficient, but it is in practice vastly more efficient than what came before (bunches of physical boxes to handle all the heterogeneity in software dependencies). -- RPM _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
