Re: hotplug error after several starting multiple VMs

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Thu, Aug 26, 2010 at 09:21:40PM -0400, Cris Daniluk wrote:
> Okay, trying a new combination of Xen release/dom0. I'm running
> OpenSLES 11.3 with dist kernel 2.6.34-12-xen using dist
> 4.0.0_21091_05-6.6.  In general, behavior is good and I am able to
> fire and put VMs under load. However, I'm running into hotplug errors
> after starting around 20 VMs. I've had very poor results trying to
> research this problem given the overwhelming number of people who see
> the error message when configuring Xen for the first time, so I'm not
> sure where to begin debugging. Everything is running under a single

It looks as if the hot plug scripts are the ones that fail. Here is what
I would suggest:

 1). Enable all debug options in /etc/sysconfig/xend
 2). Add -x to the hotplug scripts, as so:
[konrad@phenom /]$ diff -uNr /etc/xen/scripts/block.orig
/etc/xen/scripts/block
--- /etc/xen/scripts/block.orig 2010-08-27 12:05:05.383410805 -0400
+++ /etc/xen/scripts/block      2010-08-27 12:05:09.438365152 -0400
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/bash -x
 
 dir=$(dirname "$0")
 . "$dir/block-common.sh"

That will make the output of whatever the script is doing and as well
all the errors it encountered be logged in /var/log/xen/xen-hotplug.log

You probably want to add the -x to the network-bridge script.

> bridge and I'm using Xen's network-bridge script to manage it. Once I
> get into this state, I can't start new VMs, but I can continue to work
> with the VMs that are already running. The error is as follows:
> 
> linux:/etc/xen/shared/domains # xm create test13
> Using config file "./test13".
> Error: Device 0 (vif) could not be connected. Hotplug scripts not working.
> 
> 
> The xend.log output is below. Nothing is logged to xen-hotplug.log.

Try the -x trick and that file should be filled with data.