Xen devel - Nov 2003 - Changelog, FreeBSD, images, and experiences

Hello,

I''m looking at running Xen and have a few non-technical questions :)

1)  Is there a ChangeLog anywhere?  I did not find one on the website. I
suspect it may be in BitKeeper, but I haven''t gotten that far yet.

2) Is there any status /  website / mailing list for the FreeBSD port?

3) I''m looking for user experiences with running virtual servers on
different hardware.   Does anyone wish to share their experiences with
how many virtual servers they''ve been able to load on servers and the
specs and workload?  How well they performed would be nice too.

--
Thank you,
Matt Ayres



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> Hello,
> 
> I''m looking at running Xen and have a few non-technical questions
:)
> 
> 1)  Is there a ChangeLog anywhere?  I did not find one on the website. I
> suspect it may be in BitKeeper, but I haven''t gotten that far yet.
There''s effectively a changelog on the xen.bkbits.net web site,
but I suspect it''s too fine grained to be useful to anyone but
the developers. Whenever we add significant new functionality
(which seems to be happening at least once a week at the moment!)
something gets posted to xen-devel. However, I suspect having an
''executive summary'' changelog would be very useful for real
users.
> 2) Is there any status /  website / mailing list for the FreeBSD port?
Currently, there''s only one intrepid volunteer (hi Kip!) working
on it, so there hasn''t been need for a specific mailing list. 
> 3) I''m looking for user experiences with running virtual servers
on
> different hardware.   Does anyone wish to share their experiences with
> how many virtual servers they''ve been able to load on servers and
the
> specs and workload?  How well they performed would be nice too.
How long is a piece of string ;-)

It''s so dependent on all the guest''s workload and the
performance
of the particular machine. For some applications e.g. honeypots,
running hundreds of domains might be appropriate, for others,
just a couple per CPU. The worst case overhead we''ve ever seen
running applications each in their own guest vs. running them
under the same OS is just a few percent. Some times you actually
go faster because of no buffer cache interference etc.

Best,
Ian




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On Fri, 2003-11-14 at 09:06, Ian Pratt wrote:
> There''s effectively a changelog on the xen.bkbits.net web site,
> but I suspect it''s too fine grained to be useful to anyone but
> the developers. Whenever we add significant new functionality
> (which seems to be happening at least once a week at the moment!)
> something gets posted to xen-devel. However, I suspect having an
> ''executive summary'' changelog would be very useful for
real
> users.
> 
Yes, a summary changelog would be nice.  I''m looking for it so I can
look for possible features that I do not know exist yet and then try to
find out how to use it from the code :)
> > 3) I''m looking for user experiences with running virtual
servers on
> > different hardware.   Does anyone wish to share their experiences with
> > how many virtual servers they''ve been able to load on servers
and the
> > specs and workload?  How well they performed would be nice too.
> 
> How long is a piece of string ;-)
> 
> It''s so dependent on all the guest''s workload and the
performance
> of the particular machine. For some applications e.g. honeypots,
> running hundreds of domains might be appropriate, for others,
> just a couple per CPU. The worst case overhead we''ve ever seen
> running applications each in their own guest vs. running them
> under the same OS is just a few percent. Some times you actually
> go faster because of no buffer cache interference etc.
> 
I guess i''ll have to rely on my own testing then :)  I was just
wondering what other peoples experiences were so I could get a larger
picture of the general opinion of Xen.


I do have one technical question, has anyone used any other method of
virtual disks besides the one included (ie. loopback files, LVM) ?
Pardon me not trying this out first, i''m still building the Xen /
XenoLinux images on my (slow) test box.


--
Thanks,
Matt Ayres
> Best,
> Ian
> 
> 
> 
> 
> -------------------------------------------------------
> This SF.Net email sponsored by: ApacheCon 2003,
> 16-19 November in Las Vegas. Learn firsthand the latest
> developments in Apache, PHP, Perl, XML, Java, MySQL,
> WebDAV, and more! http://www.apachecon.com/
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/xen-devel


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> I do have one technical question, has anyone used any other method of
> virtual disks besides the one included (ie. loopback files, LVM) ?
> Pardon me not trying this out first, i''m still building the Xen /
> XenoLinux images on my (slow) test box.
Currently, domain''s virtual block devices can be backed by either
real ''raw'' disk partitions, or by ''virtual
disks'' which are
files in a custom file system (not unlike VMware''s VMFS).

There''s currently no way to intercept block requests and redirect
them to another domain for inspection/execution, but this sort of
thing will obviously have to be considered by the team developing
the generic ''debug'' interface. 

One option would be to have Xen turn block requests received on
certain virtual block device interfaces into fake network packets
that are delivered to a privileged domain. We could use the same
format for the packets as e.g. ENBD, and hence just run a
modified ENBD user-space server to do whatever intervention we
wanted. 

For most domains, I current use NFS to a server in domain0.

Ian



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