Hypervisors and you!
dfussell at byu.edu
Fri Mar 15 11:12:24 MDT 2013
On 03/15/2013 10:38 AM, Gabriel Gunderson wrote:
> On Fri, Mar 15, 2013 at 8:12 AM, Tod Hansmann<plug.org at todandlorna.com> wrote:
>> - I'm looking at Xen, but don't know much about it yet
> Xen was the stuff back in the day. It's still widely used, but mostly
> by those with tons of existing investment and build out in their
> infrastructure. It was the obvious choice 7 or 8 years ago (has it
> really been that long?).
Xen still rocks. With Citrix getting involved, things have changed;
like the move to a Windows management client, and the fact that they
over complicated XenServer/XenEnterprise and started charging as much as
VMware. But the Xen community stuff has been going strong for some
time, and most of the new development happens there anyway. Citrix has
finally started opening up their Xen distro with the Xen Cloud Platform
(XCP/XAPI), but I haven't had much success getting XAPI working in
Debian. It's still tied pretty heavily to CentOS. There is command
line management for XCP, but it's really complicated. Every last piece
has a giant UUID to specify, the documentation is not so thorough.
There are some bash command completion for it now, but I still don't
like it. The plus side is, they have the signed paravirt drivers for
windows in XCP without having to buy the big Citrix XenServer. Other
things I don't like about XCP are the reliance on the Microsoft VHD
format and it's 2TB limit, and the scripts that used to all be in python
are now all in ocaml. I really don't see what that bought them that
they didn't already have with python. There is an open source Open Xen
Manager client for linux that tried to duplicate the windows client, but
it crashes often enough to be irritating, and it looks like it's gone stale.
Now that I've scared you away from XCP, the xen community stuff is still
great. I think the new Xen scripts are still in python, the XAPI has
made it much easier to have it managed with Nova, or libvirt, or
xenlight (the new community stack), etc. Arbitrary python is no longer
allowed in the config files, but I never really used that in the first
place. With xentools, I can have a nice, slim paravirt debian vm up in
about 15 minutes, basically however long it takes rpm/debootstrap to
pull the needed files from a repository. Networking is now all handled
by your distro scripts/configs (/etc/network/interface for debian). I
didn't like this at first, but once I ran through it the first time, I
realized it was easier than the old network bridge scripts, and only
slightly different than configuring additional ethernet cards anyway; so
it's still nice and simple.
I started out running xen with virt-manager on SuSE, but found it much
easier with just the standard command line xen stuff. I tried to do
libvirt a few times since, but often ran into things I could do easily
with the xm command line interface that I couldn't do with libvirt. I
don't think I've missed much without libvirt.
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