Re: [Xen-users] Hotplug scripts not working / problem with loopback driver

[Tim Sharpe <tim.sharpe@xxxxxxxxxxxxxxxxxxx>]

Do the required number of loop devices actually exist? If not cd /dev;
MAKEDEV loop<number> and try again.

--Tim

Craig Webster wrote:
> Hi list,
> 
> I'm having a bit of an annoying problem which, being new to Xen and  the
> loopback device, I have no idea how to fix.
> 
> Everything was running along fine with 4 VMs, I attempted to add a  5th
> VM and it couldn't connect to the backend devices. A quick Google 
> suggested that increasing the max_loop parameter for the kernel 
> (loopback driver is compiled in, not a module) would fix this so I 
> added that param to my grub.conf and rebooted.
> 
> When I tried to start any of the previously working VMs I now get  this
> happening:
> 
>   saturn vm # xm create subversion.cfg -c
>   Using config file "subversion.cfg".
>   Error: Device 769 (vbd) could not be connected. Hotplug scripts  not
> working.
>   saturn vm # xm destroy subversion
>   saturn vm # xm create subversion.cfg -c
>   Using config file "subversion.cfg".
>   Error: Device 770 (vbd) could not be connected. Backend device not 
> found.
>   saturn vm # xm destroy subversion
>   saturn vm # xm create subversion.cfg -c
>   Using config file "subversion.cfg".
>   Error: Device 770 (vbd) could not be connected. Backend device not 
> found.
> 
> I have since tried removing the max_loop param from my grub.conf and 
> rebooting but the same problem keeps coming up.
> Google suggested removing the memory limit on dom0 but that didn't  make
> any difference; I still got the same error.
> 
> Looking at the logs it appears that there's something wrong with my 
> loopbacks or block hotplug script, but I don't know enough to know  what
> to Google for next.
> 
> Commenting out the disk parameter in my vm config file allows the  boot
> process to get much further (until it tries to mount the disks).
> 
> These are the log entries:
>   saturn vm # tail /var/log/xen-hotplug.log
>   mkdir: cannot create directory `/var/run/xen-hotplug/block': File  exists
>   mkdir: cannot create directory `/var/run/xen-hotplug/block': File  exists
>   [... repeated lots ...]
>   mkdir: cannot create directory `/var/run/xen-hotplug/block': File  exists
>   ioctl: LOOP_SET_FD: Device or resource busy
> 
>   saturn vm # tail /var/log/xend.log
>       return self.dom.waitForDevices()
>     File "/usr/lib64/python2.4/site-packages/xen/xend/
> XendDomainInfo.py", line 1343, in waitForDevices
>       self.waitForDevices_(c)
>     File "/usr/lib64/python2.4/site-packages/xen/xend/
> XendDomainInfo.py", line 971, in waitForDevices_
>       return self.getDeviceController(deviceClass).waitForDevices()
>     File "/usr/lib64/python2.4/site-packages/xen/xend/server/
> DevController.py", line 135, in waitForDevices
>       return map(self.waitForDevice, self.deviceIDs())
>     File "/usr/lib64/python2.4/site-packages/xen/xend/server/
> DevController.py", line 151, in waitForDevice
>       raise VmError("Device %s (%s) could not be connected. "
>   VmError: Device 770 (vbd) could not be connected. Backend device  not
> found.
> 
> My subversion.cfg looks like this:
> 
>   saturn vm # cat subversion.cfg
>   kernel = "/var/vm/vmlinuz-2.6-xenU"
>   memory = 64
>   ip = "aaa.bbb.ccc.ddd" # This is a public IP in the cfg file
>   netmask = "255.255.255.192"
>   gateway = "aaa.bbb.ccc.ddd" # As is this
>   vif = ['bridge=xenbr0']
>   name = "subversion"
>   disk = ['file:/var/vm/subversion-hd.img,sda1,w','file:/var/vm/
> subversion-swap.img,sda2,w']
>   root = "/dev/sda1 ro"
> 
> If you have any suggestions which could help me get these VMs running 
> again they would be much appreciated.
> 
> Cheers,
> Craig
> 
> ps apologies for the length of the post -- wanted to include as much 
> information as possible.
> -- 
> Craig Webster | t: +44 (0)131 516 8595 | e: craig@xxxxxxxxxx
> Xeriom.NET    | f: +44 (0)131 661 0689 | w: http://xeriom.net
> 
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> Xen-users mailing list
> Xen-users@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-users
> 


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