Xen users - Jun 2011 - GRUB stopped working in xen (hvm, qemu-dm)

Hi,

first of all, my name is Karsten and I am fairly new to xen. A former colleague 
of mine has set up a xen dom0 with 4 virtual machines runnig on it. A few months
ago this colleague left the company. Last week our office Building has been hit 
by a lightning wich resulted in an power blackout.

After the power went back again, the system booted and all but one of the 
virtual machines went back. The virtual machine that did not went back seems not
to be able to boot, i see some kind of grub error. The console of this machine 
prints out:

====Plex86/Bochs VGABios current-cvs 07 Jun 2008
This VGA/VBE Bios is released under the GNU LGPL
Please visit :
 * http://bochs.soureeferge.net
 * http://www.nongnu.org/vgabios
cirrus-compatible VGA is detected
HVMAssist BIOS, 1 Cpu, $Revision: 1.138 $ $Date: 2005/05/07 15:55:26 $
ata0 master: QEMU HARDDISK ATA-7 Hard-Disk (35840 MBgtes)
ata0 slave: Unknown device
ata1 master: masteri QEMU CD-ROM ATAPI-4 CD-Rom/DVD-Rom
ata1 slave: Unknown device
Booting from Hard Disk...
GRUB GRUB _
====
After this, the boot process hangs and the vm seems to be verry busy, CPU goes 
up to 100%.

The host system seems to be OpenSuSE 11.0, while the virtual machine is running 
debian 4.0.

The configuration of this virtual machine:

===erde:/ # cat /etc/xen/vm/VM4
name="VM4"
uuid="67896e91-b77f-edcc-48c8-ef3016821ecd"
memory=512
vcpus=2
on_poweroff="destroy"
on_reboot="restart"
on_crash="destroy"
localtime=0
builder="hvm"
extid=0
device_model="/usr/lib/xen/bin/qemu-dm"
kernel="/usr/lib/xen/boot/hvmloader"
boot="c"
disk=[ ''file:/var/lib/xen/images/VM4/disk0,hda,w'',
''phy:/dev/cdrom,hdc:cdrom,r'',
]
vif=[ ''mac=00:16:3e:62:62:80,model=rtl8139,type=ioemu'', ]
stdvga=0
vnc=1
vncunused=1
apic=0
acpi=1
pae=1
serial="pty"
===
I tried to attach the DomU disk image of this machine to Dom0 using xm 
bock-attach and it worked. All files are there, e2fsck did not find any errors.

So my question is, how can i recover this virtual machine? I there a chance to 
re-install grub? What is the meaning of this "GRUB GRUB" printed out
by grub?

Thanks in advance,
Karsten

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On Wed, Jun 15, 2011 at 5:14 AM, Karsten von Hornbostel
<perlmeister@yahoo.de> wrote:
> Hi,
>
> first of all, my name is Karsten and I am fairly new to xen. A former
colleague
> of mine has set up a xen dom0 with 4 virtual machines runnig on it. A few
months
> ago this colleague left the company. Last week our office Building has been
hit
> by a lightning wich resulted in an power blackout.
>
bad luck for sure.
> After the power went back again, the system booted and all but one of the
> virtual machines went back. The virtual machine that did not went back
seems not
> to be able to boot, i see some kind of grub error. The console of this
machine
> prints out:
>
> ====> Plex86/Bochs VGABios current-cvs 07 Jun 2008
> This VGA/VBE Bios is released under the GNU LGPL
> Please visit :
>  * http://bochs.soureeferge.net
>  * http://www.nongnu.org/vgabios
> cirrus-compatible VGA is detected
> HVMAssist BIOS, 1 Cpu, $Revision: 1.138 $ $Date: 2005/05/07 15:55:26 $
> ata0 master: QEMU HARDDISK ATA-7 Hard-Disk (35840 MBgtes)
> ata0 slave: Unknown device
> ata1 master: masteri QEMU CD-ROM ATAPI-4 CD-Rom/DVD-Rom
> ata1 slave: Unknown device
> Booting from Hard Disk...
> GRUB GRUB _
> ====>
> After this, the boot process hangs and the vm seems to be verry busy, CPU
goes
> up to 100%.
>
> The host system seems to be OpenSuSE 11.0, while the virtual machine is
running
> debian 4.0.
>
> The configuration of this virtual machine:
>
> ===> erde:/ # cat /etc/xen/vm/VM4
> name="VM4"
> uuid="67896e91-b77f-edcc-48c8-ef3016821ecd"
> memory=512
> vcpus=2
> on_poweroff="destroy"
> on_reboot="restart"
> on_crash="destroy"
> localtime=0
> builder="hvm"
> extid=0
> device_model="/usr/lib/xen/bin/qemu-dm"
> kernel="/usr/lib/xen/boot/hvmloader"
> boot="c"
> disk=[ ''file:/var/lib/xen/images/VM4/disk0,hda,w'',
''phy:/dev/cdrom,hdc:cdrom,r'',
> ]
> vif=[ ''mac=00:16:3e:62:62:80,model=rtl8139,type=ioemu'', ]
> stdvga=0
> vnc=1
> vncunused=1
> apic=0
> acpi=1
> pae=1
> serial="pty"
> ===>
> I tried to attach the DomU disk image of this machine to Dom0 using xm
> bock-attach and it worked. All files are there, e2fsck did not find any
errors.
>
> So my question is, how can i recover this virtual machine? I there a chance
to
> re-install grub? What is the meaning of this "GRUB GRUB" printed
out by grub?
>
Looks like the master boot record got messed up and/or grub is broken.
You can boot your domU guest from a live CD by changing the boot
parameter to:

boot="dc"
and adding a ISO file for a cdrom drive

see an example here:
http://www.novell.com/communities/node/3046/how-boot-paravirtual-xen-domu-cd-rom-or-iso-sles-10-sp1-or-opensuse-103

Thanks,
Todd
> Thanks in advance,
> Karsten
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users
>


-- 
Todd Deshane
http://www.linkedin.com/in/deshantm
http://www.xen.org/products/cloudxen.html
http://runningxen.com/

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>> So my question is, how can i recover this virtual machine? I there a
chance
to
>> re-install grub? What is the meaning of this "GRUB GRUB"
printed out by grub?
>>
> Looks like the master boot record got messed up and/or grub is broken.
> You can boot your domU guest from a live CD by changing the boot
> parameter to:
> boot="dc"
> and adding a ISO file for a cdrom drive
> see an example here:
>http://www.novell.com/communities/node/3046/how-boot-paravirtual-xen-domu-cd-rom-or-iso-sles-10-sp1-or-opensuse-103
>3
Thanks, that worked. The system is up an running again.

Regards,
Karsten

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Hi Karsten &all

2011/6/15 Karsten von Hornbostel
<perlmeister@yahoo.de>:
> disk=[ ''file:/var/lib/xen/images/VM4/disk0,hda,w'',
''phy:/dev/cdrom,hdc:cdrom,r'',
> ]
I think this should be changed to read "tap:aio:/var/lib..." instead
of file:/var/lib..."
The performance will be better and it will reduce the amount of
caching that the linux buffer cache does on your "disk image file".

That should help with the next lightning strike :)

Flo

-- 
the purpose of libvirt is to provide an abstraction layer hiding all
xen features added since 2006 until they were finally understood and
copied by the kvm devs.

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