Re: [Xen-users] XENBUS timeout connecting to device (Hard disks not detected)

["Philippe-A. Lemelin" <philippe.lemelin@xxxxxxxxxxxx>]

On 15-01-05 08:09 AM, Ian Campbell wrote:
> On Tue, 2014-12-30 at 08:58 -0500, Philippe-A. Lemelin wrote:
> > Good Morning List,
> >
> > I'm currently trying to install a CentOS DomU
> What is your dom0? Also CentOS? If so which Xen and libvirt are you
> using (built yourself, from packages on the net, etc)?
Yes, my dom0 is a fully updated CentOS 6. The xen version is 4.2.5-37 
and the libvirt version is 0.10.2.8-8. All installed from the xen4 rpm 
repository of CentOS. We also reinstalled the machine so it's a fresh 
install with the default configurations.
Strangely, I have more than one server now running those versions of 
packages and my domU are not showing any issues at the moment. I will 
try to launch an installation on those and see if it can detect the disks.
> >   and I am facing an issue I
> > never experienced before. None of my hard disks are detected. I've now
> > tried with a single HDD or with many as I usually do and each time, I'm
> > faced with the same result. I tried with a CenOS 5 and 6 DomU with the
> > same end result, the installer is not seeing any valid devices on which
> > to install.
> >
> > Here is the command i'm using when launching the installation:
> >
> > virt-install --vnc --bridge=xenbr0 -p --name=test --ram=2000 --vcpus=2
> > --disk /images/disk1.img,format=raw --disk /images/disk2.img,format=raw
> > --disk /images/disk3.img,format=raw --disk /images/disk4.img,format=raw
> > --disk /images/disk5.img,format=raw
> > --location=http://mirror.centos.org/centos/5/os/x86_64
> >
> > When looking at the installer log I see the following ( I confirmed that
> > the 5 devices that timeout are indeed the xvda, xvdb... disks):
> >
> > <6>XENBUS: Device with no driver: device/vbd/51712
> > <6>XENBUS: Device with no driver: device/vbd/51728
> > <6>XENBUS: Device with no driver: device/vbd/51744
> > <6>XENBUS: Device with no driver: device/vbd/51760
> > <6>XENBUS: Device with no driver: device/vbd/51776
> > <6>XENBUS: Device with no driver: device/vif/0
> > <6>XENBUS: Device with no driver: device/console/0
> > ...
> > <4>XENBUS: Waiting for devices to initialise: 295s...290s... ...
> > ...
> > <4>XENBUS: Timeout connecting to device: device/vbd/51712 (local state
> > 3, remote state 1)
> > <4>XENBUS: Timeout connecting to device: device/vbd/51728 (local state
> > 3, remote state 1)
> > <4>XENBUS: Timeout connecting to device: device/vbd/51744 (local state
> > 3, remote state 1)
> > <4>XENBUS: Timeout connecting to device: device/vbd/51760 (local state
> > 3, remote state 1)
> > <4>XENBUS: Timeout connecting to device: device/vbd/51776 (local state
> > 3, remote state 1)
> >
> > Once the installation fails, If I connect with Virt-Manager, I can see
> > that my machines has 5 disks attached. I do not understand why it is
> > timing out like that.
> >
> > I'm looking for any debugging tips or pointers on helping me to resolve
> > this rather strange issue.
> Wild stab in the dark: Is the backend driver present in dom0? Either the
> kernel module loaded or the appropriate backend provider (qemu perhaps)
> installed and getting launched?
>
> The output of "xenstore-ls -fp" while the guest is running would contain
> some clues as to which backend is expected, which might suggest a next
> step.
I've run this command on my working installation and I can see it is 
using tap2 :
/vm/6acf630f-912b-7159-8188-b7a7afd4d3f2/device/tap2 = ""   (n0)
/vm/6acf630f-912b-7159-8188-b7a7afd4d3f2/device/tap2/51712 = ""   (n0)
/vm/6acf630f-912b-7159-8188-b7a7afd4d3f2/device/tap2/51712/frontend = 
"/local/domain/12/device/vbd/51712"   (n0)
/vm/6acf630f-912b-7159-8188-b7a7afd4d3f2/device/tap2/51712/frontend-id = 
"12"   (n0)
/vm/6acf630f-912b-7159-8188-b7a7afd4d3f2/device/tap2/51712/backend-id = 
"0"   (n0)
/vm/6acf630f-912b-7159-8188-b7a7afd4d3f2/device/tap2/51712/backend = 
"/local/domain/0/backend/vbd/12/51712"   (n0)
On the installation that is causing me issue, it would seem it is using 
tap :
/vm/81ac93e8-8e79-a3ea-7039-7eabc0ed8b86/device/tap = ""   (n0)
/vm/81ac93e8-8e79-a3ea-7039-7eabc0ed8b86/device/tap/51712 = ""   (n0)
/vm/81ac93e8-8e79-a3ea-7039-7eabc0ed8b86/device/tap/51712/frontend = 
"/local/domain/5/device/vbd/51712"   (n0)
/vm/81ac93e8-8e79-a3ea-7039-7eabc0ed8b86/device/tap/51712/frontend-id = 
"5"   (n0)
/vm/81ac93e8-8e79-a3ea-7039-7eabc0ed8b86/device/tap/51712/backend-id = 
"0"   (n0)
/vm/81ac93e8-8e79-a3ea-7039-7eabc0ed8b86/device/tap/51712/backend = 
"/local/domain/0/backend/tap/5/51712"   (n0)
I will try to force the driver to tap2 during the installation with 
driver_name=tap2,driver_type=aio.
> There are also various logs under /var/log/xen and presumably some
> libvirt logs somewhere which would be worth having a look at.
I went through all the logs under /var/log/xen (tail -f /var/log/xen/*) 
during the installation of my machine and could not see errors.
I will go through the libvirt logs and see if more information is available.

> Do you know which toolstack libvirt is talking to, either xend or libxl.
Where can I find this information ?

> Ian.
Thank you for you time Ian !

Philippe-A. Lemelin


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