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

To: Dennis Krul <dweazle@xxxxxxxxx>
Subject: Re: [Xen-devel] Xend crashes, how to debug?
From: Andrew Lyon <andrew.lyon@xxxxxxxxx>
Date: Mon, 30 Nov 2009 15:32:28 +0000
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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
> (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

I seem to recall threads about running xend in a stubdom so that might
be a option.


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