[ntp:questions] Flash 400 on all peers; can't get ntpd to be happy
malayter at gmail.com
Mon Mar 14 18:50:57 UTC 2011
On Fri, Mar 11, 2011 at 12:47 PM, John Hasler <jhasler at newsguy.com> 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
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