Re: Xen
Manuel Bouyer
> [...]
> It isn't perfect stuff, in addition NetBSD currently only has Xen3
> support paravirtualized --
NetBSD runs fine on Xen4 too.
--
Manuel Bouyer <bou...@antioche.eu.org>
NetBSD: 26 ans d'experience feront toujours la difference
--
--
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Alex Goncharov
| > It isn't perfect stuff, in addition NetBSD currently only has Xen3
| > support paravirtualized --
|
| NetBSD runs fine on Xen4 too.
Can NetBSD run a Xen4 host? (With what guest OSes, would be nice to
know but this is probably not a question to ask on a NetBSD list.)
-- Alex -- alex-go...@comcast.net --
Ben C.
<alex-go...@comcast.net> wrote:
> ,--- You/Ben (Tue, 2 Aug 2011 19:38:44 -0500) ----*
> | I am an AVID xen user -- I run my dom0 on NetBSD and also have 2 pleasantly
> | running NetBSD domu's without issue. And also -- just adding -- I occasionally
> | run a netbsd HVM under Xen's version of qemu to do some testing.
>
> [ I want to be educated on this ]
>
> When I researched it a couple of years ago, I came to several
> conclusions on Xen:
>
> * A guest of a NetBSD won't use more than one CPUs.
This is being worked on, and I don't mean to flaunt but I was hinted
that there /may/ be decent code
merged into -CURRENT in the coming months.
It isn't perfect stuff, in addition NetBSD currently only has Xen3
support paravirtualized --
I really don't understand the major differences between Xen3 & Xen4
but from what I
can grasp from the Xen community it's mostly bug fixes and relatively
minor improvements.
Now, keep in mind, on the dom0 you can run the Xen4 Hypervisor and
related tools,
and still use the the NetBSD Xen3 Kernel because it's backwards-compatible, but
as much as I wish I could tell you, I have no idea what the
implications of all this are
really.
>
> * Xen does not mix well with FreeBSD (I don't remember the details).
This is mostly due to lack of FreeBSD support -- no offense to them -- but
I *think* it's fairly accurate. I actually have a standing bug with
freebsd-xen@
right now where I can't use FreeBSD as a HVM with more than 1 virtual CPU
(which is odd). Probably a problem with qemu which isn't xen-specific, or maybe
Xen is just being a piece of crap. I don't know, and wish I did.
If you'd like to follow that just read my post there, on the FreeBSD
mailing lists.
Otherwise, I have few issues. That one issue was a doozy, I will admit.
Yes, it's not the cleanest configuration in the world but FreeBSD/xen support is
being worked on fairly actively. FreeBSD also has experimental PV support but
I've yet to find time to try it.
>
> So, of Unixes, only a Linux/NetBSD mixes can be seriously
> considered.
I've been using NetBSD -CURRENT + Xen for a little over a year for
production servers and maintaining about 98.8% uptime minus some
reboots I'm not counting. Keep in mind, I said -CURRENT, not -STABLE
which may/may not be more reliable. I do use Linux guests/domu's on
a daily basis for my own reasons, but *BSD powered stuff just helps
me sleep at night. Maybe I'm biased, or even ignorant, but it's how
I do business.
>
> * I also had frustrating Xen configuration problems when I went from
> hosting it on NetBSD 4 to NetBSD 5. Something about network
> interfaces, IIRC.
It's confusing to comment on this because I don't know if you mean a
NetBSD dom0 or a NetBSD domu, but I'd be happy to help you with any
specific error messages or problems over at the ports-xen@netbsd mailing
list, along with everyone else subscribed there, provided we have time
and the knowledge :)
Out of my domu's (running on a NetBSD dom0), -- NetBSD and CentOS
are the easiest I've had to configure with both having no issues running
paravirtualized. OpenBSD actually comes in third, I think, running as a HVM.
OpenBSD for some reason needed model=e1000 in it's vif=[] line, but it's
a quirky little thing in itself.
>
> Can you comment on any of these points?
>
> | In my opinion, NetBSD will soon be the choice OS for virtualization.
>
> Why do you think so?
Read http://netbsd.org/about/interop.html
I think, a simple "plus" of a NetBSD dom0.
>
> I am no expert, but it seems to me that VirtualBox gets much more
> attention (and is, in my experience, easier to configure and use).
> But VirtualBox is probably not a NetBSD strength, or is it?
Honestly I'm not familiar with VirtualBox, but that big ORACLE logo
turns me off right off the bat. Sure, Citrix plastering it's logo all over Xen
isn't the highlight of my day either, but at the end of the day, I'll
pick Citrix
over Oracle any day (to be completely biased and generalized about it)
You may also find this petty, but keep in mind Rackspace and Amazon EC2
both use Xen (although, I'm sure heavily modified versions at this
point). I think
it's safe to say it's fairly proven technology.
> | Just wish it would get there sooner. I see all kinds of people
> | report problems that they have issues with Xen's networking, Xen's
> | this, Xen's that,
>
> Precisely what I remember, from the two-three years ago. Ultimately,
> why fight it, when there are easier options? I might have been
> impatient, but still... VirtualBox on FreeBSD worked out of the box.
> Performance was such, though, that I abandoned its use soon, too. With
> the current modest costs of hardware...
Although I have pretty heavy hardware running my domu's on my NetBSD box,
other than some disk i/o bottlenecks I have, I get pretty decent performance.
Not that I'm satisfied with it. It could always be better, ESPECIALLY
with the fact
I'm only using 1 out of 4 cores on my systems.
Just use your judgement. If you're more comfortable with
Linux stuff, well try it. Linux has KVM, which I know nothing about,
other than the
fact it's a linux-only kernel module.
As I said, I'm also unfamiliar with VirtualBox, which also doesn't
seem to run on
any *BSD.
Then -- there is Xen. FreeBSD/Xen support, is, as you even said, kind
of shoddy.
The domu support is quirky to say the least and dom0 support is of course
nonexistent. OpenBSD support is 10 years away (if ever -- kind of out of scope
to elaborate) .. and that leaves NetBSD -- which, in my own possibly biased
opinion is the PERFECT place to get some very decent virtualization.
Niels Dettenbach
> VirtualBox is useless for large-scale virtualization. A Xen domu runs at
> almost host speed, with very little overhead
Full ACK,
even if we've still seen some mid scale university or company NOCs where the
CTOs / admins are really working with headless VirtualBox as their "main HV".
Especially if your main target is to run open source based operating systems
like Linux or NetBSD (on i386/686) on NOC scale XEN PV was and is - so my
point and for several different reasons (performance, stability, scalability)
- the best choice in any case. We hardly want to and do avoid any full
virtualization on internet servers.
We use XEN since the early stages in many different productive environments -
compared and compare all the current major virtualization solutions around -
from VMware products over kvm to VirtualBox. It is interesting to hear and
read what kind of "crazy" stories or just "misunderstandings" are around about
xen i.e. compared to VMware - i.e. from VMware marketers...
VirtualBox is our preferred HV on typical Desktop environment (because of the
easier graphics acceleration and USB stuff), but i hope that en will close up
here too...
cheers,
Niels.
--
---
Niels Dettenbach
Syndicat IT&Internet
http://www.syndicat.com/
Manuel Bouyer
> ,--- You/Manuel (Wed, 3 Aug 2011 17:40:36 +0200) ----*
> | > It isn't perfect stuff, in addition NetBSD currently only has Xen3
> | > support paravirtualized --
> |
> | NetBSD runs fine on Xen4 too.
>
> Can NetBSD run a Xen4 host?
Yes, you have the xentools4 and xenkernel4 packages in pkgsrc
> (With what guest OSes, would be nice to
> know but this is probably not a question to ask on a NetBSD list.)
the same as with Xen 3.
--
Manuel Bouyer <bou...@antioche.eu.org>
NetBSD: 26 ans d'experience feront toujours la difference
Alex Goncharov
| I am an AVID xen user -- I run my dom0 on NetBSD and also have 2 pleasantly
| running NetBSD domu's without issue. And also -- just adding -- I occasionally
| run a netbsd HVM under Xen's version of qemu to do some testing.
[ I want to be educated on this ]
When I researched it a couple of years ago, I came to several
conclusions on Xen:
* A guest of a NetBSD won't use more than one CPUs.
* Xen does not mix well with FreeBSD (I don't remember the details).
So, of Unixes, only a Linux/NetBSD mixes can be seriously
considered.
* I also had frustrating Xen configuration problems when I went from
hosting it on NetBSD 4 to NetBSD 5. Something about network
interfaces, IIRC.
Can you comment on any of these points?
| In my opinion, NetBSD will soon be the choice OS for virtualization.
Why do you think so?
I am no expert, but it seems to me that VirtualBox gets much more
attention (and is, in my experience, easier to configure and use).
But VirtualBox is probably not a NetBSD strength, or is it?
| Just wish it would get there sooner. I see all kinds of people
| report problems that they have issues with Xen's networking, Xen's
| this, Xen's that,
Precisely what I remember, from the two-three years ago. Ultimately,
why fight it, when there are easier options? I might have been
impatient, but still... VirtualBox on FreeBSD worked out of the box.
Performance was such, though, that I abandoned its use soon, too. With
the current modest costs of hardware...
-- Alex -- alex-go...@comcast.net --
Julio Merino
> Hello,
>
> In an earlier post I asked about why people like NetBSD and one person
> mentioned Xen. Since then I've been browsing the mail archives and I've
> seen Xen come up a few times. I'm going to ask a question that might be
> tremendously stupid, but if I don't ask I'll never learn:
>
> Isn't Xen just a virtual machine like QEMU, VirtualBox, etc? What makes
> Xen special that people here talk about it while they don't talk about
> QEMU and VirtualBox?
Xen is a paravirtualization system: it requires changes to the guest
operating systems, unlike QEMU or VirtualBox which run unmodified
systems. NetBSD has built-in support for Xen, while the support for
Linux has always been distributed as a set of patches (for reasons
unknown to me).
This scheme allows for higher performance of the virtual machines.
I recommend you to read the "Xen and the Art of Virtualization" paper:
www.cl.cam.ac.uk/research/srg/netos/papers/2003-xensosp.pdf
Kind regards,
--
Julio Merino / @jmmv
Greg Troxel
Isn't Xen just a virtual machine like QEMU, VirtualBox, etc? What
makes Xen special that people here talk about it while they don't talk
about QEMU and VirtualBox?
With xen, it's reasonable to set up a machine as a dom0 and have a dozen
domUs on it, and to run the entire group in production for order of
years and depend on it (including booting from power-on with no human
present). I have never had the impression that qemu/virtualbox was
suitable for that.
Daniel Carrera
> With xen, it's reasonable to set up a machine as a dom0 and have a dozen
> domUs on it, and to run the entire group in production for order of
> years and depend on it (including booting from power-on with no human
> present). I have never had the impression that qemu/virtualbox was
> suitable for that.
Ok. Yeah, that sounds very different from QEMU / VirtualBox. I think
those are more geared toward a desktop user who wants to run just one or
a handful of guest OS's.
Daniel.
--
I'm not overweight, I'm undertall.
Atticus
> why fight it, when there are easier options? I might have been
> impatient, but still... VirtualBox on FreeBSD worked out of the box.
> Performance was such, though, that I abandoned its use soon, too. With
> the current modest costs of hardware...
>
> -- Alex -- alex-go...@comcast.net --
>
>
in production, just for fun) on a single-core 2.8GHz P4 with 1Gb of RAM with
for weeks at a time, with no issues. Yes, it lagged if I had them all doing
resource intensive things, but in a production environment, one would be set
up with multiple processors, gigabytes of memory, etc. VirtualBox has it's
place, don't get me wrong. It's great for those "let's test out this new
distro/OS/winblow$" times, but even on a well built box, you're very limited
by the full virtualization. Full virtualization will always be slower than
paravirtualization. The better the hardware gets, the better the
virtualization software will get, but the more complex full virtualization
becomes. Xen will always have it's pseudo-devices and the like, and
VirtualBox will always be emulating an entire processor+peripherals. There's
no way around the speed damper.
--
FT3(SU) Byron Grobe, USN
Ben C.
if your processor has support for such. So, regardless what your dom0
(host) machine is -- NetBSD or some kind of Linux -- NetBSD will run pretty much
anywhere. (But, You want it to run under paravirtualization if possible)
I am an AVID xen user -- I run my dom0 on NetBSD and also have 2 pleasantly
running NetBSD domu's without issue. And also -- just adding -- I occasionally
run a netbsd HVM under Xen's version of qemu to do some testing.
In my opinion, NetBSD will soon be the choice OS for virtualization. Just
wish it would get there sooner. I see all kinds of people report problems that
they have issues with Xen's networking, Xen's this, Xen's that, -- I never have
issues with my NetBSD -STABLE machines .. (-CURRENT is another story..
but I don't expect it not to have issues there..)
Regards, Ben
On Tue, Aug 2, 2011 at 2:16 PM, Daniel Carrera <dcar...@gmail.com> wrote:
> Hello,
>
> In an earlier post I asked about why people like NetBSD and one person
> mentioned Xen. Since then I've been browsing the mail archives and I've seen
> Xen come up a few times. I'm going to ask a question that might be
> tremendously stupid, but if I don't ask I'll never learn:
>
> Isn't Xen just a virtual machine like QEMU, VirtualBox, etc? What makes Xen
> special that people here talk about it while they don't talk about QEMU and
> VirtualBox?
>
> Thank you for your help.
>
> Cheers,
> Daniel.
> --
> I'm not overweight, I'm undertall.
>
--
Jean-Yves Migeon
> Xen is a paravirtualization system: it requires changes to the guest
> operating systems, unlike QEMU or VirtualBox which run unmodified
> systems. NetBSD has built-in support for Xen, while the support for
> Linux has always been distributed as a set of patches (for reasons
> unknown to me).
>
> This scheme allows for higher performance of the virtual machines.
>
> I recommend you to read the "Xen and the Art of Virtualization" paper:
>
> www.cl.cam.ac.uk/research/srg/netos/papers/2003-xensosp.pdf
Some additions (or corrections ;) ):
- starting with Xen 3 (a few years back), provided you have hardware
assisted virtualization, you do not need to patch guests to run under
Xen. This only applies to guest VMs though, dom0 still needs to know
that it runs with the hypervisor below so it can handle devices.
Paravirtualized drivers remain faster though, as they do not have the
extra overhead implied by emulation.
- Latest Linux revisions (3, maybe 3.1) have the support included in
vanilla kernel, and are not distributed with third party patches. They
were not included before because of technical and political reasons.
--
Jean-Yves Migeon
jeanyve...@free.fr