[rescue] Cheap, fast, PC server
pat at computer-refuge.org
Sun Jan 27 15:38:20 CST 2008
On Sunday 27 January 2008 12:40, Shannon Hendrix wrote:
> On Jan 27, 2008, at 6:16 AM, Angel Martin Alganza wrote:
> > On Sat, Jan 26, 2008 at 11:55:39PM -0500, Shannon Hendrix wrote:
> >> My big question in all this is why are people using VMs so much?
> > What about live migration of VMs across different real servers?
> I covered that when I said "you need to give someone a machine".
> Obviously that's one of those situations.
> What I see though is a lot of people using them just to virtualize
> servers, and VMs are a very expensive way to do that.
VMs aren't necessarily expensive (especially when you're using Xen, for
instance).. one good use for them is allowing a few different groups
to run light-weight servers (say a web server, or whatever), and have
root on each machine, and run whatever OS they want to on it.
Also, there are instances where you may quickly use up some resource of
the system of a machine, but still have a very light I/O and CPU load.
Things like nagios and cfengine (used at work) come to mind, as does
the server & scheduler for a PBS batch scheduler.
As someone else mentioned, live migration is pretty nice too. If you
need to upgrade the hardware, or fix the machine that you're running
on, you can live migrate the OS image over to a machine in another
building, or even a different state. So, if you have a power failure,
instead of shutting down the machine when the UPS runs out, you can
just migrate it to a machine somewhere where the power isn't out, or
that has some sort of backup power, etc.
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