One detail; the code we used in KVM had a driver name='qemu', and running that 
code right away gives the error message;

 # virsh attach-device deb cdrom7.xml                                         1 
error: Failed to attach device from cdrom7.xml
error: POST operation failed: xend_post: error from xen daemon: (xend.err 
'Block device type "qemu" is invalid.')

//Daniel

On Feb 10, 2012, at 11:24 AM, Daniel Espling wrote:

> Hi!
> 
> We're struggling to get device detaching to work reliably using Xen. We can 
> reliably use the same code to manage devices using Libvirt+KVM without any 
> problems. We've tested this on Xen with both CD-ROM and USB devices without 
> success. See below for detailed descriptions.
> 
> Thankful for any help!
> 
> Regards,
> Daniel Espling
> 
> ---
> 
> For CD-ROM, we can mount them using attach-device but cannot remove them 
> using the correspoding call to detach-device:
> 
> cdrom7.xml contains:
> <disk type='file' device='cdrom'>
>       <driver name='file' type='raw'/>
>       <source file='/opt/diskimages/test7.iso'/>
>       <target dev='hdc' bus='ide'/>
>       <readonly/>
> </disk>
> 
> eject.xml contains:
> <disk type='block' device='cdrom'>
>       <driver name='file'/>
>       <target dev='hdc' bus='ide'/>
>       <readonly/>
> </disk>
> 
> cdrom8.xml is identical to cdrom7.xml apart from the .iso file used.
> 
> # virsh attach-device deb cdrom7.xml                                          
>  
> Device attached successfully
> 
> # virsh detach-device deb cdrom7.xml                                          
>  
> error: no such device in deb
> 
> # virsh attach-device deb eject.xml
> error: Failed to attach device from eject.xml
> error: POST operation failed: xend_post: error from xen daemon: (xend.err 
> 'Device 5632 not connected')
> 
> # virsh update-device deb cdrom8.xml --persistent
> error: Failed to update device from cdrom8.xml
> error: POST operation failed: xend_post: error from xen daemon: (xend.err 
> 'Device 5632 not connected')
> 
> dumpxml shows the cdrom device attached exactly as it's defined in the xml.
> 
> Using virsh we're able to use "virsh detach-disk deb hdc" to unmount the 
> CD-ROM, but we need to be able to do this using the python API. We cannot 
> find a corresponding call to detach-disk and we therefore have to rely on 
> detach-device instead, right? Are there any flags we can use for 
> detachDeviceFlags() to replicate the functionality of detach-disk?
> 
> ----
> 
> Similarly for USB devices, we can mount them OK but not remove them using the 
> corresponding call to detach-device. Calling detach-disk works, but again we 
> need to find the corresponding call for this function using the python API. 
> One thing we've found with mounting USB devices is that they seem to be 
> mounted on the SCSI bus instead of the USB one as specified:
> 
> Example:
> 
> usb7.xml contains:
> <disk type='file' device='disk'>
>       <driver name='file' type='raw'/>
>       <source file='/opt/diskimages/test7.iso'/>
>       <target dev='sda' bus='usb'/>
>       <readonly/>
> </disk>
> 
> dumpxml shows:
> <disk type='file' device='disk'>
>       <driver name='file'/>
>       <source file='/opt/diskimages/test7.iso'/>
>       <target dev='sda' bus='scsi'/>
>       <readonly/>
> </disk>
> 
> # virsh attach-device deb usb7.xml
> Device attached successfully
> 
> Test attaching again (expected to fail):
> # virsh attach-device deb usb7.xml                                            
>  
> error: Failed to attach device from usb7.xml
> error: Requested operation is not valid: target 'sda' already exists
> 
> `-testgrid7.leeds.ac.uk /opt/recontext # virsh detach-device deb usb7.xml
> error: no such device in deb
> 
> ----
> 
> Relevant info:
> 
> Compiled against library: libvir 0.9.9
> Using library: libvir 0.9.9
> Using API: Xen 0.9.9
> Running hypervisor: Xen 4.0.0
> 
> Running CentOS 5.5 (final)
> Linux 2.6.32.24 #3 SMP Fri Oct 29 16:22:02 BST 2010 x86_64 x86_64 x86_64 
> GNU/Linux
> _______________________________________________
> libvirt-users mailing list
> [email protected]
> https://www.redhat.com/mailman/listinfo/libvirt-users

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