12 Jun
2009
12 Jun
'09
8:35 a.m.
On Fri, Jun 12, 2009 at 03:51:18PM +0100, Liam Proven wrote:
Thanks everyone who shared information on this topic. I suspected there
had been VM's done before, I was surprised by some of the incarnations.
<snip>
I'm
curious, what OS:es and software did virtualisation before
VMware/XEN/Virtualbox and the like ?
Answered in detail by others, but I'd also point out some non-OS
hypervisors that were around long before VMware etc. Sheep Shaver on
BeOS in 1998, for instance. And finaly,
why would keeping virtual installations up to date be any
harder than non-virtual?
great servers running all those as guests, you *still*
have 50 copies
of Windows to maintain. The work level doesn't drop much at all - you
just save space and electricity.
</snip>
This was my point, the work level doesn't drop, but it certainly does
not increase!
And even that is a partly illusory saving, because
much of the power
and resources that a computer will use in its typical working life of
a few years is spent in building the thing. So by replacing multiple
working hardware boxes with a single big new machine to run the same
workloads, you're wasting all that sunk-cost of the manufacture of
those boxes, while "spending" a load more non-recoverable resources
that were used to make the new box.
Well that all depends on the load. Recently we moved two low-load
machines into a virtual environment, perhaps we didn't cut the
power/cooling costs in half, but it's certainly an improvement.
Let's say you're running 4 copies of Windows, in VMs, on a host copy
of Windows. That's 5 gig of RAM and 4,500MHz of CPU bandwidth blown on
all those copies of Windows, of which 4.5GB and 4000MHz are running
duplicated code that is shared by all the VMs.
In this case I agree that virtualization is probably a bad idea. But if
the client OS needs 250MB worth of memory and a few percent of the CPU.
You could easily squeeze three of them into 1GB (asuming the host OS
needs only 250 MB, which might be optimistic). Also think of the case
where the client systems doesn't need the CPU all the time.
If, instead, you were running an OS that could partition itself so
that the 4 workloads all ran on the same shared kernel, but completely
isolated from one another, so that one could have one version of the
core libraries and another a different version,
This would be awsome, is there any such system? My guess is that it is
very hard to get right. However you totally miss the case where you need
different operating systems.
Does that make my point clear?
Yes, I see that there are cases where virtualization is really stupid.
But I hope that my argumentation for the cases where it is smart make
sense :)
Cheers,
Pontus.