Re: [libvirt] Mounting a raw DVD

Adam Mooz <adam.mooz@xxxxxxxxx> · Tue, 10 Nov 2009 09:18:07 -0500

On 2009-11-10, at 12:48 AM, Gerry Reno wrote:

Adam Mooz wrote:
On 2009-11-09, at 11:46 PM, Gerry Reno wrote:

Adam Mooz wrote:
Hello List,

I'm attempting to pass a DVD drive of a headless server into a virtual machine.  So far I've managed to mount *something* into the VM, but it's being registered as a blank DVD within the VM. When I mount /dev/dvd into the bare-metal machine it registers normally as the DVD.  How do I pass physical drives into a VM and back out using libvirt?  Command used:
#virsh attach-disk Montreal /dev/dvd hdc --mode readonly --driver phy --type cdrom
Connecting to uri: qemu:///system
Disk attached successfully

VM XML file:

<domain type='kvm'>
 <name>Montreal</name>
 <uuid>0f79ba7f-27bf-16a0-5887-6cfa2b5569f1</uuid>
 <memory>2097152</memory>
 <currentMemory>2097152</currentMemory>
 <vcpu>1</vcpu>
 <os>
   <type arch='x86_64' machine='pc-0.11'>hvm</type>
   <boot dev='hd'/>
 </os>
 <features>
   <acpi/>
   <apic/>
   <pae/>
 </features>
 <clock offset='utc'/>
 <on_poweroff>destroy</on_poweroff>
 <on_reboot>restart</on_reboot>
 <on_crash>restart</on_crash>
 <devices>
   <emulator>/usr/bin/kvm</emulator>
   <disk type='file' device='cdrom'>
     <target dev='hdc' bus='ide'/>
     <readonly/>
   </disk>
   <disk type='file' device='disk'>
     <source file='(Mangled Purposely)'/>
     <target dev='vda' bus='virtio'/>
   </disk>
   <interface type='bridge'>
     <mac address='(mangled purposly)/>       <source bridge='br0'/>
     <model type='virtio'/>
   </interface>
   <serial type='pty'>
     <target port='0'/>
   </serial>
   <console type='pty'>
     <target port='0'/>
   </console>
   <input type='mouse' bus='ps2'/>
   <graphics type='vnc' port='-1' autoport='yes' keymap='en-us'/>
   <video>
     <model type='cirrus' vram='9216' heads='1'/>
   </video>
 </devices>
</domain>

I haven't done this for a while but I believe you have to issue a 'detach' command afterwards.

-Gerry

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# virsh detach-disk Montreal hdc
Connecting to uri: qemu:///system
error: this function is not supported by the hypervisor: only SCSI or virtio disk device can be detached dynamically

? Also, I'm not sure if you understood my question.  When I pass in the DVD device into the VM it registers as a blank DVD.  if I pass in a non-existant folder it blows up, so I know it's reading something from the real DVD drive.  Mounting the real DVD drive in the bare-metal machine shows the files on the drive, but I cannot get them to appear in the VM.  How do I get the same files to show up in the VM (i.e. mount the DVD drive into the VM)?

I didn't see /dev/dvd in your xml.  If you attach it and then dump the xml what does it look like?  And then have you tried booting the VM with an xml file with this device and can you read the files on the device this way?

The other thing is that maybe your version of libvirt is too old.  I think 0.7.1 is current.

-Gerry

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Booting with the drive specified within the XML also gives a blank DVD in the VM, no luck there. It turns out I'm running libvirt 7.0, was there a large change between 7.0 and 7.1 in the way they handle mounting block devices?  

Here is some more output:
After mounting at runtime, not at boot to the VM.
virsh # dumpxml Montreal
<domain type='kvm' id='3'>
  <name>Montreal</name>
  <uuid>0f79ba7f-27bf-16a0-5887-6cfa2b5569f1</uuid>
  <memory>2097152</memory>
  <currentMemory>2097152</currentMemory>
  <vcpu>4</vcpu>
  <os>
    <type arch='x86_64' machine='pc-0.11'>hvm</type>
    <boot dev='hd'/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <pae/>
  </features>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <emulator>/usr/bin/kvm</emulator>
    <disk type='block' device='cdrom'>
      <source dev='/dev/dvd'/>
      <target dev='hdc' bus='ide'/>
      <readonly/>
    </disk>
    <disk type='file' device='disk'>
      <source file='/mnt/vmdrive/Montreal-ubuntu-media/montreal.vmdk'/>
      <target dev='vda' bus='virtio'/>
    </disk>
    <interface type='bridge'>
      <mac address='54:52:00:63:bf:8d'/>
      <source bridge='br0'/>
      <target dev='vnet0'/>
      <model type='virtio'/>
    </interface>
    <serial type='pty'>
      <source path='/dev/pts/1'/>
      <target port='0'/>
    </serial>
    <console type='pty' tty='/dev/pts/1'>
      <source path='/dev/pts/1'/>
      <target port='0'/>
    </console>
    <input type='mouse' bus='ps2'/>
    <graphics type='vnc' port='5900' autoport='yes' keymap='en-us'/>
    <video>
      <model type='cirrus' vram='9216' heads='1'/>
    </video>
  </devices>
  <seclabel type='dynamic' model='apparmor'>
    <label>libvirt-0f79ba7f-27bf-16a0-5887-6cfa2b5569f1</label>
    <imagelabel>libvirt-0f79ba7f-27bf-16a0-5887-6cfa2b5569f1</imagelabel>
  </seclabel>
</domain>

virsh # version
Compiled against library: libvir 0.7.0
Using library: libvir 0.7.0
Using API: QEMU 0.7.0
Running hypervisor: QEMU 0.11.0

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Adam Mooz
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AdamMooz@xxxxxx
http://www.AdamMooz.com

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