Re: [gentoo-user] VMs - what technology would you advise?

[J. Roeleveld]

On Wednesday, December 31, 2014 09:42:11 AM Rich Freeman wrote:
> On Wed, Dec 31, 2014 at 8:26 AM, Mick <michaelkintzios@×××××.com> wrote:
> > On Wednesday 31 Dec 2014 12:47:55 Sid S wrote:
> >
> > Vbox seems to be coming last by quite some margin in the intel tests!  I
> > also read this article and it looks that vbox is thankfully doing better
> > on AMD; but there are differences in the versions and kernels used
> > between the two
> > articles:
> I think you need to think about your use case.  The requirements were
> for a workstation testing environment.  I think performance (as long
> as somewhat reasonable) isn't going to be a big concern there vs ease
> of setup, ability to snapshot,

The thing lacking from KVM (and I believe also Containers) is that the memory 
contents are not included in snapshots. Making the snapshots basically result 
in an unclean-shutdown scenario.
Which is ok-ish as a backup, but not when testing different steps where a quick 
and easy roll-back is often required.

> convenience features like being able to
> group guests, being able to get the right environment easily, etc.
> You probably also want reasonable graphics performance if you're
> testing clients inside VMs.  If performance makes the difference
> between being able to run the cluster you need to test on your
> workstation or not, then that becomes a factor.  Otherwise it is a
> nice-to-have.
>
> If you're talking about running servers then performance becomes much
> more important.  However, if you're running linux guests you should
> seriously consider containers, and if containers aren't the right
> solution you should also be looking at stuff like VMWare (I don't know
> how well the FOSS solutions do as far as enterprise-y features go).

I compared the ease-of-use and performance between XenServer, VMWare and 
VirtualBox.
VMWare generally is the slower of the three.
Also, the weird errors occuring when VMs are migrated between nodes in a 
VMWare cluster makes me worry every time I hear it's being used for critical 
systems.

> In any case, while not quite as simple as Virtualbox I've found that
> virt-manager is very easy to use once you've gotten networking set up
> (which isn't too hard to do under either openrc or networkd).  I tend
> to use the GUI for setting things up and for graphical guests, and I
> used to create init.d scripts / units for the stuff that I
> subsequently moved to containers.  You can go back-and-forth between
> the two (and to be fair you can do the same with virtualbox).  One of
> the advantages of KVM is that it doesn't require tainting your kernel,

That is an advantage of KVM and Xen over Virtualbox and VMWare.

> and you don't have to remember to rebuild the module anytime you
> update your kernel.  I've finally gotten to the point where I don't
> have any external modules on one of my boxes and I'm very happy with
> that (alas, my mythtv frontend needs nvidia-drivers - I don't think
> the hardware acceleration is as good with the kernel drivers though to
> be fair it has been a year or two since I last tried).

I tend to use the nvidia-drivers where I need graphics. But those machines are 
not VMs.
If graphical performance is a requirement, NVidia cards (apart from the 
expensive professional ones) are best avoided. They are actively crippled in a 
VM environment.

--
Joost