Re: [Xen-devel] Xend crashes, how to debug?

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Mon, Nov 30, 2009 at 03:32:28PM +0000, Andrew Lyon wrote:
> On Mon, Nov 30, 2009 at 2:51 PM, Dennis Krul <dweazle@xxxxxxxxx> wrote:
> > Hi,
> >
> > We have a very annoying issue we've been unable to iron out. I've googled
> > and browsed through the complete xen-devel and xen-user archives, but it
> > seems we're the only ones having this issue, although I somehow doubt we
> > really are.
> >
> > Once in a while xend simply crashes. When we don't touch anything it will
> > keep running without problems. But sometimes, usually when we run 'xm
> > create', xend crashes, leaving a 'Domain-Unnamed' behind, which we then have
> > to destroy manually. Quite annoying, especially when your provisioning runs
> > completely unattended.
> >
> > We don't have any idea where to look. The xen logs are completely useless,
> > no clue what could be wrong whatsoever. A strace didn't provide much useful
> > info and nothing related in the output of 'xm dmesg' either.
> >
> > I suspect the problem is caused by an I/O bottleneck. I noticed that ever
> > since I moved the xenstore to a ramdisk (tmpfs), xend crashes less often,
> > but it still happens.. If our I/O bottleneck is indeed the problem, how can
> > I verify that? And shouldn't xend be more resilient against these types of
> > issues? Have there been any patches in xend related to such issues? Can I
> > increase the verbosity of xend logging perhaps?
> >
> > Some background info: We run Xen 3.3.2 on Fedora 11 with Linux 2.6.30.7
> > (Fedora 11 kernel with forward ported Xen patches from OpenSUSE). Maybe it's
> > an unusual setup, but apart from this issue it's actually perfectly stable.
> > We didn't have much luck with Xen 3.4, so we decided to stick with 3.3.2 for
> > now. The dom0 has 1Gb memory, which should be enough (and most of it is
> > unused).
> >
> > Can anyone point us into the right direction on how to debug this issue? I
> > don't have much knowledge about xen internals, so I'd appreciate any
> > pointers. Thanks! :)
> >
> > --
> > Dennis Krul <dweazle@xxxxxxxxx>
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
> >
> >
> 
> The Xenserver product uses a different xend which is written in ocaml
> and is supposed to be a lot more robust, I believe somebody rewrote
> the open source xend in ocaml for the same reasons so you could try
> that.
> 
> I seem to recall threads about running xend in a stubdom so that might
> be a option.
> 

And XenServer is opensource now.. so you could always try the ocaml
xend.

Althought I'm not sure if it's easy/direct replacement..

-- Pasi


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