[Users] Physical CDROM access

Dan Kenigsberg danken at redhat.com
Tue Dec 17 14:39:58 UTC 2013

On Mon, Dec 16, 2013 at 10:23:36AM -0500, Bob Doolittle wrote:
> On 12/16/13 08:44, Dan Kenigsberg wrote:
> >On Mon, Dec 16, 2013 at 09:58:15AM +0200, Itamar Heim wrote:
> >>On 12/13/2013 09:15 PM, Bob Doolittle wrote:
> >>>Hi,
> >>>
> >>>With VMware ESX, when you edit the CD device you have of course the
> >>>option of attaching an ISO, but IIRC you also have the option of
> >>>selecting the physical CDROM device for the Host.
> >>>
> >>>There seems no way to do this with oVirt. It would be a really nice
> >>>addition to the "Change CD" menu to have something like "/dev/cdrom". Is
> >>>there a technical issue preventing this? Of course that would prevent VM
> >>>migration such as HA while the CDROM device is attached, but that didn't
> >>>stop VMware and it would be a valuable addition.
> >>>
> >>>Thanks,
> >>>     Bob
> >>>
> >>>_______________________________________________
> >>>Users mailing list
> >>>Users at ovirt.org
> >>>http://lists.ovirt.org/mailman/listinfo/users
> >>1. at some point i hope spice will allow this to connect remote
> >>    cd-rom's and install from them.
> >>2. please open an RFE (bugzilla) to track this.
> >>3. you can use a custom hook for this - an adaption on hostusb, or
> >>    maybe even vmdisk would work. if you need help with the custom hook,
> >>    just ping back on the list.
> >I think Bob asked to access the /dev/cdrom device of the host machine,
> >not the one of the spice client.
> That's right. I never even thought of the spice client case.
> Although that also sounds useful it would be much more complex.
> Luckily it's not what I need. I'll file that RFE in any case since
> it does sound useful, in addition to this one.
> >Bob, if that's the case, I think you can do it by circomventing Engine
> >and calling `vdsClient -s <host> changeCD /dev/cdrom`; please try it
> >out.
> It appears this command is slightly incorrect, I believe it should be:
> vdsClient -s <host> changeCD <VM-UUID> /dev/cdrom

thanks for the correction.

> when I try this, however, I get an error: "Failed to change disk image"
> I've attached the vdsm.log file. There is also one suspicious entry
> in syslog, although I think it was from before I tried this
> particular command:
> Dec 16 10:03:57 xion2 vdsm vm.Vm WARNING
> vmId=`99f89b62-d8e2-4ffd-b2e1-e471beff63b6`::_readPauseCode
> unsupported by libvirt vm
> I had previously tried a 'list table' and a 'help' command to see
> how vdsClient worked. It is more likely a result of one of those
> given the timestamp.

The answer is in the log: "No medium found".
Could you retry with a cd inside?

Thread-311::DEBUG::2013-12-16 10:09:36,221::BindingXMLRPC::974::vds::(wrapper) client []::call vmChangeCD with ('99f89b62-d8e2-4ffd-b2e1-e471beff63b6', '/dev/cdrom') {}
Thread-311::INFO::2013-12-16 10:09:36,222::clientIF::350::vds::(prepareVolumePath) prepared volume path: /dev/cdrom
Thread-311::DEBUG::2013-12-16 10:09:36,307::libvirtconnection::108::libvirtconnection::(wrapper) Unknown libvirterror: ecode: 38 edom: 18 level: 2 message: cannot open file '/dev/cdrom': No medium found
Thread-311::DEBUG::2013-12-16 10:09:36,307::vm::4150::vm.Vm::(_changeBlockDev) vmId=`99f89b62-d8e2-4ffd-b2e1-e471beff63b6`::updateDeviceFlags failed
Traceback (most recent call last):
  File "/usr/share/vdsm/vm.py", line 4148, in _changeBlockDev
    diskelem.toxml(), libvirt.VIR_DOMAIN_DEVICE_MODIFY_FORCE)
  File "/usr/share/vdsm/vm.py", line 835, in f
    ret = attr(*args, **kwargs)
  File "/usr/lib64/python2.6/site-packages/vdsm/libvirtconnection.py", line 76, in wrapper
    ret = f(*args, **kwargs)
  File "/usr/lib64/python2.6/site-packages/libvirt.py", line 1755, in updateDeviceFlags
    if ret == -1: raise libvirtError ('virDomainUpdateDeviceFlags() failed', dom=self)
libvirtError: cannot open file '/dev/cdrom': No medium found
Thread-311::DEBUG::2013-12-16 10:09:36,325::BindingXMLRPC::981::vds::(wrapper) return vmChangeCD with {'status': {'message': 'Failed to change disk image', 'code': 41}}

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