Re: [Xen-users] newbie xen problens with vbd

[John <info@xxxxxx>]

JC,

Take a look at your /dev/loop files: I am copying the text below from
our intranet (found it from various sources on the internet though):

"Error: Device 769 (vbd) could not be connected. Backend device not
found.

This is caused by a insufficient number of loop devices.

Try: ls -l /dev/loop* and see what it does. I have seen occasions where
there's only a /dev/loop/0 for some reason:

john@pr01:~$ ls -l /dev/loop*
brw------- 1 root root 7, 0 2006-12-29 00:07 0

However on our production hosts, we create many more loop devices:

remoteadmin@vs01:~$ ls -l /dev/loop<tab>
Display all 128 possibilities? (y or n)
n

If you have the loop driver compiled into your kernel, you need to add
max_loop=64 (or whatever number of loop devices you wish to use for Xen) 
to your kernel boot arguments (the append= line in
lilo.conf, or to the end of the kernel line in grubs menu.lst), and
reboot.

If you have the loop driver compiled as a module, you need to insmod it
with max_loop=64 added to its options. On Debian systems, you edit
/etc/modules.conf and add options loop max_loop=64, and rmmod loop
modprobe loop.

If youre using devfs, then stop here. The new /dev/loop* will appear
automatically. If not, youll need to edit and run MAKEDEV: Change:

       loop)
               for part in 0 1 2 3 4 5 6 7
               do
                       makedev loop$part b 7 $part $disk
               done
               ;;

To:

       loop)
               for part in `seq 0 63`
               do
                       makedev loop$part b 7 $part $disk
               done
               ;;

And run MAKEDEV loop. This is only necessary if you need more than 8
guests by the way. 

Xen can work really well but it takes some time to learn what the ~5-10
most common error messages mean that you can expect. We have them all on our
intranet - typically the messages are quite .. cryptic .. so to say :-)

HTH

John

On Tue, Feb 20, 2007 at 02:44:05AM -0300, JC Júnior wrote:
> Date: Tue, 20 Feb 2007 02:44:05 -0300
> From: JC Júnior <junior.listas@xxxxxxxxx>
> To: xen-users <xen-users@xxxxxxxxxxxxxxxxxxx>
> Subject: [Xen-users] newbie xen problens with vbd
> 
> hi all; first of all, sorry for long message...
> 
>    I'm new in xen and using debian sarge as dom0 with xen 3.0.3  ( 
> 3.0.4 does not work perfectly ), everything works nice ( make world, 
> make install ),  I created successfully one debian sarge domU ( like 
> howtoforge howto ), an set a config file:
> #----debian_base-----------------------------------
> kernel = "/boot/vmlinuz-2.6-xen"
> name = "debianbase"
> memory = 64
> cpu=0
> disk = [ "file:/vserver/debian.base/debian.base.img,sda2,w" ]
> root = "/dev/sda2 ro"
> vif = [ '' ]  #its only for test
> #--------------------------------------------------------------
> 
> and when i type:  xm create -c debian_base shows:
> 
> Using config file "debian_base".
> Error: Device 2050 (vbd) could not be connected. Backend device not found.
> 
> After this, the domU stops...
> I have a look in log files and  I did not find nothing that made very 
> sensible for me, but here go some snippets:
> 
> # /var/log/messages
> Feb 20 02:33:49 localhost kernel: device vif9.0 entered promiscuous mode
> Feb 20 02:33:49 localhost kernel: ADDRCONF(NETDEV_UP): vif9.0: link is 
> not ready
> Feb 20 02:33:50 localhost kernel: xenbr0: port 3(vif9.0) entering 
> disabled state
> Feb 20 02:33:50 localhost kernel: device vif9.0 left promiscuous mode
> Feb 20 02:33:50 localhost kernel: xenbr0: port 3(vif9.0) entering 
> disabled state
> 
> #/var/log/syslog
> Feb 20 02:33:49 localhost kernel: device vif9.0 entered promiscuous mode
> Feb 20 02:33:49 localhost kernel: ADDRCONF(NETDEV_UP): vif9.0: link is 
> not ready
> Feb 20 02:33:49 localhost logger: /etc/xen/scripts/vif-bridge: 
> Successful vif-bridge online for vif9.0, bridge xenbr0.
> Feb 20 02:33:49 localhost logger: /etc/xen/scripts/vif-bridge: Writing 
> backend/vif/9/0/hotplug-status connected to xenstore.
> Feb 20 02:33:50 localhost logger: /etc/xen/scripts/block: add 
> XENBUS_PATH=backend/vbd/9/2050
> Feb 20 02:33:50 localhost logger: /etc/xen/scripts/block: Writing 
> backend/vbd/9/2050/hotplug-status error to xenstore.
> Feb 20 02:33:50 localhost logger: /etc/xen/scripts/block: 
> /vserver/debian.base/debian.base.img does not exist.
> Feb 20 02:33:50 localhost kernel: xenbr0: port 3(vif9.0) entering 
> disabled state
> Feb 20 02:33:50 localhost kernel: device vif9.0 left promiscuous mode
> Feb 20 02:33:50 localhost kernel: xenbr0: port 3(vif9.0) entering 
> disabled state
> Feb 20 02:33:50 localhost logger: /etc/xen/scripts/vif-bridge: offline 
> XENBUS_PATH=backend/vif/9/0
> Feb 20 02:33:50 localhost logger: /etc/xen/scripts/vif-bridge: brctl 
> delif xenbr0 vif9.0 failed
> Feb 20 02:33:50 localhost logger: /etc/xen/scripts/vif-bridge: ifconfig 
> vif9.0 down failed
> Feb 20 02:33:50 localhost logger: /etc/xen/scripts/vif-bridge: 
> Successful vif-bridge offline for vif9.0, bridge xenbr0.
> Feb 20 02:33:50 localhost logger: /etc/xen/scripts/xen-hotplug-cleanup: 
> XENBUS_PATH=backend/vif/9/0
> Feb 20 02:33:50 localhost logger: /etc/xen/scripts/block: remove 
> XENBUS_PATH=backend/vbd/9/2050
> Feb 20 02:33:50 localhost logger: /etc/xen/scripts/block: Writing 
> backend/vbd/9/2050/hotplug-status error to xenstore.
> Feb 20 02:33:50 localhost logger: /etc/xen/scripts/block: xenstore-read 
> backend/vbd/9/2050/node failed.
> Feb 20 02:33:50 localhost logger: /etc/xen/scripts/block: Writing 
> backend/vbd/9/2050/hotplug-status error to xenstore.
> Feb 20 02:33:50 localhost logger: /etc/xen/scripts/block: 
> /etc/xen/scripts/block failed; error detected.
> Feb 20 02:33:50 localhost logger: /etc/xen/scripts/xen-hotplug-cleanup: 
> XENBUS_PATH=backend/vbd/9/2050
> 
> #/var/log/xen/xen-hotplug.log
> Nothing to flush.
> xenstore-read: couldn't read path backend/vbd/9/2050/node
> 
> #/var/log/xen/xend.log
> [2007-02-20 02:33:49 xend 7876] DEBUG (DevController:143) Waiting for 
> devices vif.
> [2007-02-20 02:33:49 xend 7876] DEBUG (DevController:149) Waiting for 0.
> [2007-02-20 02:33:49 xend 4572] DEBUG (DevController:464) 
> hotplugStatusCallback /local/domain/0/backend/vif/9/0/hotplug-status.
> [2007-02-20 02:33:49 xend 4572] DEBUG (DevController:464) 
> hotplugStatusCallback /local/domain/0/backend/vif/9/0/hotplug-status.
> [2007-02-20 02:33:49 xend 4572] DEBUG (DevController:478) 
> hotplugStatusCallback 1.
> [2007-02-20 02:33:50 xend 7876] DEBUG (DevController:143) Waiting for 
> devices usb.
> [2007-02-20 02:33:50 xend 7876] DEBUG (DevController:143) Waiting for 
> devices vbd.
> [2007-02-20 02:33:50 xend 7876] DEBUG (DevController:149) Waiting for 2050.
> [2007-02-20 02:33:50 xend 4572] DEBUG (DevController:464) 
> hotplugStatusCallback /local/domain/0/backend/vbd/9/2050/hotplug-status.
> [2007-02-20 02:33:50 xend 4572] DEBUG (DevController:464) 
> hotplugStatusCallback /local/domain/0/backend/v[2007-02-20 02:33:49 xend 
> 7876] DEBUG (DevController:143) Waiting for devices vif.
> [2007-02-20 02:33:49 xend 7876] DEBUG (DevController:149) Waiting for 0.
> [2007-02-20 02:33:49 xend 4572] DEBUG (DevController:464) 
> hotplugStatusCallback /local/domain/0/backend/vif/9/0/hotplug-status.
> [2007-02-20 02:33:49 xend 4572] DEBUG (DevController:464) 
> hotplugStatusCallback /local/domain/0/backend/vif/9/0/hotplug-status.
> [2007-02-20 02:33:49 xend 4572] DEBUG (DevController:478) 
> hotplugStatusCallback 1.
> [2007-02-20 02:33:50 xend 7876] DEBUG (DevController:143) Waiting for 
> devices usb.
> [2007-02-20 02:33:50 xend 7876] DEBUG (DevController:143) Waiting for 
> devices vbd.
> [2007-02-20 02:33:50 xend 7876] DEBUG (DevController:149) Waiting for 2050.
> [2007-02-20 02:33:50 xend 4572] DEBUG (DevController:464) 
> hotplugStatusCallback /local/domain/0/backend/vbd/9/2050/hotplug-status.
> [2007-02-20 02:33:50 xend 4572] DEBUG (DevController:464) 
> hotplugStatusCallback /local/domain/0/backend/vbd/9/2050/hotplug-status.
> [2007-02-20 02:33:50 xend 4572] DEBUG (DevController:478) 
> hotplugStatusCallback 2.
> [2007-02-20 02:33:50 xend.XendDomainInfo 8000] DEBUG 
> (XendDomainInfo:1449) XendDomainInfo.destroy: domid=9
> bd/9/2050/hotplug-status.
> [2007-02-20 02:33:50 xend 4572] DEBUG (DevController:478) 
> hotplugStatusCallback 2.
> [2007-02-20 02:33:50 xend.XendDomainInfo 8000] DEBUG 
> (XendDomainInfo:1449) XendDomainInfo.destroy: domid=9
> 
> #/var/log/xen/xend-debug.log
> 
> dont show anything ---
> 
> 
> I found lots information about on google, but nothing helped, somebody 
> can help me??
> 
> JC
> 
> 
> ps. sorry my bad english
> 
> 
> 
> 
> 
> 
> 
> 
> 
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