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Date:      Tue, 29 May 2012 00:48:16 +0200
From:      Witold Baryluk <baryluk@smp.if.uj.edu.pl>
To:        Lukas Laukamp <lukas@laukamp.me>
Cc:        freebsd-xen@freebsd.org
Subject:   Re: FreeBSD Xen Dom0 Support
Message-ID:  <20120528224815.GE16584@smp.if.uj.edu.pl>
In-Reply-To: <4FC3FB04.8050500@laukamp.me>
References:  <4FC3B195.8020007@laukamp.me> <B6F285C4-47B8-429C-896F-DBC32E39F91A@sysconfig.org.uk> <4FC3C83B.503@laukamp.me> <20120528220305.GC16584@smp.if.uj.edu.pl> <4FC3FB04.8050500@laukamp.me>

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On 05-29 00:24, Lukas Laukamp wrote:
> Am 29.05.2012 00:03, schrieb Witold Baryluk:
> >On 05-28 20:47, Lukas Laukamp wrote:
> >>Am 28.05.2012 20:02, schrieb Carsten Heesch:
> >>>Hi Lukas,
> >>>
> >>>>[...] I don't know whether there is support for Xen Dom0 on FreeBSD.
> >>>Unfortunately there isn't.
> >>>
> >>>>I read that NetBSD support Xen Dom0 [...]
> >>>I haven't tried myself, but apparently NetBSD works rather well as Dom0. That has long been on my list of things to test, though :)
> >>>
> >>>Not sure if you are aware of it, but in order to run FreeBSD as DomU, you don't need FreeBSD or NetBSD as Dom0. That works just as well on your Debian Dom0. (With FreeBSD's known limitations as DomU, namely memory and architecture depending on PV or HVM virtualisation)
> >>>
> >>>
> >>>Cheers
> >>>C.
> >>>
> >>>
> >>Hello Carsten,
> >>
> >>thanks for your fast answer. That FreeBSD as DomU runs on Linux I
> >>know. So I only think that it is a bit tricky to build a PV DomU of
> >>FreeBSD because the kernel must be modified. I wan't to have another
> >>system like Linux as the host because I think that the BSDs are
> >>better in the stability and a few other points. I read in the
> >>english Wikipedia article about Xen that there is support for
> >>NetBSD, OpenBSD and OpenSolaris
> >>(http://en.wikipedia.org/wiki/Xen#Host:_Unix-like_systems).
> >>
> >
> >BTW. I read yeasterday that Windows Server 2008 with Hyper-V is able to
> >run XEN PV domU Linux on it. It probably is also able to run other Xen
> >domU guests, but probably nobody was trying to do so. I do not know
> >details, but it was what I read about Hyper-V hypervisor on Wikipedia.
> >In fact it looks like independent implementation of Xen compatible
> >hypervisor (it uses same hypercall api, but I do not know with which
> >version of Xen it is compatible) with Windows as dom0.
> >
> >Not that anybody would want to run it, but just saying.
> >
> Hello Witold,
> 
> Hyper-V can do that because Microsoft has co-operation contracts
> with Citrix who is one of the primary maintainers of Xen. So the try
> to build compatibility between Xen and Hyper-V. Personaly I wouldn't
> use Hyper-V because it's not that great like for example VMWares
> vSphere.
> 
Ah, yes Citrix. This makes sense.


> But for the productive working I use Xen and KVM at the moment. And
> as I started to think to change to BSD I first looked which
> virtualization technologies are available on BSD. I thought that the
> best solution would be Xen because KVM don't is available for BSD
> and other solutions like QEmu, VirtualBox or the BSD Hypervisor
> BHyVe are very great for testing and home and so I would say the
> development command and control center but not for server
> virtualization or other things which provides services which are
> needed for productive use.
> 
> When I look at the wikis and read about the support for Xen on other
> unix like systems I only see NetBSD or Solaris (and it's forks) for
> a realy good Dom0.
> 
> So does someone can explain the differences between FreeBSD and
> NetBSD? I see not so much without looking for the supported hardware
> platforms. The BSD with the most differences I think is OpenBSD.
> 
> And the other thing is that I never worked with Solaris, but it
> seems that they have great Xen support. So I don't know whether it
> would be a good choice. I think that I will have much to learn to
> work good with a BSD but I hope it's possible for me.
> 

I personally would like to switch to FreeBSD domO mainly due to the ZFS
storage (its snapshots, easier atomic backups and zvol, fast cloning,
and easier exporting via iSCSI). I know I can do almost all of it using
LVM, just not so easly and reliabiliy or automatically.

I currently use Debian GNU/Linux, and I'm very happy, espcially due
package system, but considering there is Debian kfreebsd, I would like
to make switch in the future when domO will be available. I now use
kfreebsd (with 9.0 kernel) as domU without bigger issues.

As of NetBSD i have no idea of good distinguishing differences. It is
more portable than FreeBSD for sure (which its domO support proofs), but
there is many small differences, including hardware drivers or various
subsystems scalability performance for examples. I belive there is still
code exchange between various BSD operating systems due similar
internals and libearal licensing (especially networking code and
networking drivers).

I would somehow be carefull with Solaris, as Oracle isn't very
open-source friendly IMHO (despite its ocfs or btrfs work). I also
failed to run Solaris on the Xen, but it may be my incompetence. :(

-- 
Witold Baryluk



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