[CoLoCo] virtualization in hardy: kvm

[Neal McBurnett]

On Fri, Mar 14, 2008 at 07:29:24AM -0600, Kevin Fries wrote:
> VMWare compared to KVM is like comparing a Ferrari to a 1976 Ford Pinto.
> Both are cars (or VMMs) but only one has all the modern features; and
> only one has fine grained level of controls managing its operations; and
> only one is reliable enough to be useful.

Such comparisons are of course always misleading.  After all, there
are way more uses for virtualization than there are for cars.  VMware
may be just what you will always want - feel free to use it.  But
please don't make fun of others that don't find it at all suitable for
their purposes.

E.g. Simics is another really excellent commercial virtualization
solution, for a number of purposes.  E.g. for software development and
testing it lets you run programs BACKWARDS to find problems.  "Run
this until it crashes, then run it backwards under my control until I
find the bug".

It does this by optionally taking lots of cheap snapshots of the
entire state of the VM, and letting you unwind and inspect them when
desired.  And Simics also has very good performance, can emulate
anything on anything (like kvm) etc etc.

KVM shares many of the excellent architectural features of Simics.

So here is a different analogy.

Simics: Ferrari

The VMware stuff you pay for; a popular Ford model

Free VMware server: there is no free car analogy I can think of.
 It is more like the free samples you get from drug companies via your
 doctor.  They can be very advanced, and are intended to get you
 hooked on the stuff that costs money.  And you can't fix it if it
 breaks.  Note that it is illegal for you to share drug samples with
 other people.  This is why VMware server is not in multiverse, I
 think.

KVM - a mostly functional Magic Carpet
 Revolutionary technology that can be duplicated and distributed for
 free, imparts magical knowledge on the owners (the source code), can
 be shared with friends, emulates lots of different architectures,
 does fine-grained Copy-on-Write snapshots, is not totally mature, has
 great potential, etc. etc.

Neal McBurnett                 http://mcburnett.org/neal/