Re: [Xen-devel] Xen + other stuff?

["Gregory Newby" <newby@xxxxxxxx>]

On Thu, Nov 13, 2003 at 10:05:57PM +1300, Wesley Parish wrote:
> Oh well, I'll have to try it then.  I'm interested in getting a set of fully 
> secure Linuces running a set of RDBMSes, with application servers on top of 
> those.
> 
> Anyone hazzard a guess as to how much memory I'll be needing?  I'm certain at 
> least half a GB - but would that be per XenLinux instance?

This relates to something I bumped up against: with the current
snapshot, I've only been able to allocate about 800MB for domain0.
I am also able to allocate ~800MB for a virtual domain.

This is on a machine with 2GB of physical memory, another 4GB of swap.

When I tried to create another 800MB virtual doamin, I got
an error.  So, it seems that you're constained by physical
memory, as well as no high memory (4GB support) yet in the kernel.
Why I can only get ~800MB, rather than a full 2GB, for a particular
domain is something the developers are aware of.

Bottom line: get enough RAM for each domain (domain0 + virtuals)
to share, but the limit will be ~2GB.  When high memory support
is added, I understand the limit will be 4GB total (since that's
all the domain0 can address).  So, for a new system, 4GB would
be the max that Xen can effectively utilize in the immediate future.

Or maybe I'm wrong - I'm still trying to learn all this stuff.
How, or whether, Xen is able to utilize swap space is not clear
to me.  But my advice is to consider everything to operate
in "real" mode (i.e., no swap at all) -- it's a good way of
having enough memory, even if swapping is available.


> Wesley Parish
> 
> P.S.  I was forgetting - what's the latest Linux 2.x.x that people have had 
> running on Xen?

It's 2.4.22 (patched, of course).
  -- Greg


> On Wed, 12 Nov 2003 21:10, Steven Hand wrote:
> > >Has anyone got Xen working with say, SELinux?  Or vserver?
> >
> > We've not tried SELinux, but the vserver patch applies cleanly
> > to xenolinux and hence you can do 'two levels of virtualisation'
> > aka k vservers on n xenolinux-es on 1 xen.
> >
> > cheers,
> >
> > S.
> >
> >
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