[Xen-users] Backend device not found and domu Network eth0 SOLVED

[Etienne Duguay <eduguay@xxxxxxxx>]

Etienne Duguay wrote:

> Joe Warren-Meeks wrote:
>
> > On 28 Apr 2006, at 12:32, Abi Chirayil wrote:
> >
> > > Joe Warren-Meeks wrote:
> > >
> > > > On 27 Apr 2006, at 14:43, Joe Warren-Meeks wrote:
> > > >
> > > > Hey guys,
> > > >
> > > > > > I've installed xen 3 and xen-tools on my ubuntu server and all  
> > > > > > seems
> > > > > > well, until I try to start a client domain. (running on Linux
> > > > > > xenserver 2.6.12.6-xen #1 SMP Wed Feb 1 21:23:17 UTC 2006 i686
> > > > > > GNU/Linux)
> > > > >
> > > > >
> > > > >
> > > > > Bit of a follow-up. If I try to start the DomU, it initally  
> > > > > errors as
> > > > > so:
> > > > >
> > > > > root@xenserver:/etc/xen# xm create -c squid1.cfg
> > > > > Using config file "squid1.cfg".
> > > > > Error: Device 2049 (vbd) could not be connected. Backend device not
> > > > > found.
> > > > >
> > > > > and then shows up as paused in 'xm list'
> > > > >
> > > > > If I then attach a console to it, then unpause I see the following
> > > > > error at the end:
> > > > >
> > > > > VFS: Cannot open root device "sda1" or unknown-block(0,0)
> > > > > Please append a correct "root=" boot option
> > > > > Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-
> > > > > block(0,0)
> > > > >
> > > > > I've tried adding /dev/ nodes using MAKEDEV in both the Dom0 and  
> > > > > DomU
> > > > > and tried changing sda to hda, to no avail.
> > > > >
> > > > > Anyone got a pointer to where I can start looking?
> > > >
> > > >
> > > >
> > > > As a futher follow up, if I use xen-create-image to create a new  
> > > > domU,
> > > > this completes fine and then starts the image successfully! I can  
> > > > then
> > > > go and start all the other images and all is fine.
> > > >
> > > > Once I've halted them all and rebooted the server itself, it all  
> > > > stops
> > > > working again.
> > > >
> > > > Anyone got any pointers? This is getting quite frustrating.
> > > I'm getting exactly the same error (also using Ubuntu). I just tried
> > > mounting and unmounting the one of the images and that seems to get
> > > everything working - till the next reboot.
> > >
> > > mount -o loop /vserver/images/vmNMS.img /vserver/vm_base/
> > > umount /vserver/vm_base/
> > >
> > > Any idea why this happens? I've also been pulling my hair out the past
> > > couple of days.
> >
> >
> > Think I've fixed it.
> >
> > I read xen-create-image to see why it seemed to work if I used that.  
> > Just by an aside I noticed that there is an option of use-ide
> > So, I've set "use-ide = 1" in /etc/xen-tools/xen-tools.conf and  
> > recreated my images and it seems to work now.
>
> I don't have these files and options under FC5, are you under Debian?
>
> Is there another place where I can specify the use-ide=1 option as I 
> have the exact same problem that this solution seems to solve.
> Regards,
Ok,

For this one I've added the domU kernel the ramdisk instruction in the 
domU config. In FC5 you need both.
For the network problem I had to specify the number of nics:

kernel = "/boot/vmlinuz-2.6.16-1.2096_FC5xenU"
memory = 128
name = "centos-HSPERE"
ramdisk = "/boot/initrd-2.6.16-1.2096_FC5xenU.img"
vif = [ '' ]
nics = 1
#dhcp = "dhcp"
disk = 
['file:/img/centos.4-2.VSI,sda1,w','file:/img/centos.swap,sda2,w','file:/img/tmpfiles,sda3,w']
root = "/dev/sda1 ro"

> > I figure that an IDE server has problems trying to run a SCSI domU
> >
> > I'm creating a bunch of domUs now and rebooting to see if they all  
> > start ok. (I also had to up my loopback devices as indicated in  
> > another post)
> > Give it a shot and report back.
> >
> >  -- joe.
> >
> > Joe Warren-Meeks                       T: +44 (0) 208 962 0007
> > Aggregator Limited                     M: +44 (0) 7789 176078
> > Unit 62/63 Pall Mall Deposit           E: joe.warren-meeks@xxxxxxxxxxxxx
> > 124-128 Barlby Road, London W10 6BL
> > PGP Fingerprint: 361F 78D0 56F5 8D7F 2639  947D 71E2 8811 F825 64CC
> >
> >
> >
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--
Etienne R. Duguay 514-939-HOST (4678) ext 5
Author of/ Auteur de "Se lancer en affaires dans Internet"
ISBN 2-89521-001-2; ISBN 2-89472-062-9
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