[Discuss] choice of hypervisor (was gracefully shutdown guests)

[Edward Ned Harvey (blu)]

> From: discuss-bounces+blu=nedharvey.com at blu.org [mailto:discuss-
> bounces+blu=nedharvey.com at blu.org] On Behalf Of Greg Rundlett
> (freephile)
> 
> I find it
> helpful  to be given a list of related technologies, starting with a
> 'native' to free software hypervisor so as to be familiar with the system
> from the bare metal up.  If there are advantages to using a particular
> hypervisor, or new developments that make solution X interesting, then that
> would be a good discussion for this list.  Right?

That is a good discussion, but it's really a separate discussion.

Chuck's comment was:
> It seems many people haven't heard of the built-in native
> virtualization technology on Linux and it's management stack as
> supported by Red Hat & developed and released first on Fedora.  It is
> called KVM for Kernel-based Virtual Machine, and the userspace
> component of it uses QEmu to provide the hardware access, BIOS
> emulation, etc.  The whole thing is managed by the libvirtd daemon,
> libvirt library, command shell virsh, and installer virt-install.
> libvirt actually supports managing KVM, Xen, QEmu, LXC, OpenVZ,
> VirtualBox and VMware ESX (or so the virsh manpage claims).

So my first reaction is this:

Before there was kvm, there was xen.  And to this day, they both still exist and going strong.  But I think redhat and debian (Or Linus?  Somebody) didn't like the direction xen was going (or something like that) so a couple years ago, they switched over to kvm by default instead of xen.

Most distros also include a standard package for virtualbox, although, it's generally not installed.  You have to "yum install" or whatever for your platform ...  And even then, I prefer to download the package directly from virtualbox.org instead of using the one that's in the OS package repository.  Because I use the virtualbox oracle extensions, and it's important to always keep the GPL product (virtualbox) in-sync with the version of Oracle extensions, I find it easier to just always download the virtualbox package along with the oracle extensions package, simultaneously (and always archive together.)

I have never been very impressed with either xen or kvm, unless you're doing paravirtualization, linux guest inside linux host.  Even then, there are some shortcomings that I don't really want to get into ...  I will say this:

If you have a guest VM running on some hypervisor, then switching to a different hypervisor is often a complete pain.  One of the big reasons I like to use virtualbox is because you can run it on any host, and that makes my VM's very easily migratable between different host OSes.