Please re-test with virt-manager 0.5.3-1.fc8 available from updates-testing - it
should fix this issue.

Just done that, having re-started virt-manager and it appeared to finish but
then there was an error message:

Unable to complete install: 'Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/addhardware.py", line 513, in add_device
    self.vm.add_device(xml)
  File "/usr/share/virt-manager/virtManager/domain.py", line 729, in add_device
    raise RuntimeError, "Unable to attach device to live guest, libvirt reported
error:\n" + device_exception
RuntimeError: Unable to attach device to live guest, libvirt reported error:
virDomainAttachDevice() failed only CDROM disk devices can be attached
'

Does this mean I need to restart the VM?

I shutdown the VM and a floppy device had been created.  However, I was then
unable to start the VM in virt-manager.  The error is:

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/engine.py", line 472, in run_domain
    vm.startup()
  File "/usr/share/virt-manager/virtManager/domain.py", line 379, in startup
    self.vm.create()
  File "/usr/lib64/python2.5/site-packages/libvirt.py", line 240, in create
    if ret == -1: raise libvirtError ('virDomainCreate() failed', dom=self)
libvirtError: virDomainCreate() failed QEMU quit during console startup
qemu: could not open floppy disk image
'/dev/disk/by-id/usb-Y-E_DATA_USB_Floppy_Drive'

This error relates to device fdb, as I tried creating another floppy device, but
using a different method of referring to the 'real' device.

The mention of a 'floppy disk image' is odd, as it's not an image, but a USB
floppy drive.

I've just tried adding a USB flash drive as a device, and received a related error:

Unable to complete install: 'Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/addhardware.py", line 513, in add_device
    self.vm.add_device(xml)
  File "/usr/share/virt-manager/virtManager/domain.py", line 724, in add_device
    self.get_connection().define_domain(newxml)
  File "/usr/share/virt-manager/virtManager/connection.py", line 446, in
define_domain
    self.vmm.defineXML(xml)
  File "/usr/lib64/python2.5/site-packages/libvirt.py", line 601, in defineXML
    if ret is None:raise libvirtError('virDomainDefineXML() failed', conn=self)
libvirtError: virDomainDefineXML() failed Invalid harddisk device name: sda
'
The mention of 'sda' is odd as the device I tried to add was '/dev/sdj'.

If you'd prefer I report this as a separate bug, let me know.

The usb issue seems seperate. Please file a different bug, and specify if the
guest is running or shutdown, whether using qemu/kvm or xen, and exactly what
input you are using that triggers the issue. Thanks!

In response to comment #3: I tried to reproduce this but had no luck. That error
is what you should see if qemu can not find the specified floppy path. 

Could you try and reproduce this, and make sure that the path is still present
after the failure? If you still get the error, attach
~/.virt-manager/virt-manager.log and virsh dumpxml <domnam> to this bz.

I opened a seperate bug for the scsi issue (bz 434871), which is now fixed
upstream. Setting this bug to needinfo with regards to the info requested of
comment #3.

Have just been able to reproduce it, when using /dev/sdd as the device (it's a
USB external floppy drive):

Unable to complete install: 'Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/addhardware.py", line 513, in add_device
    self.vm.add_device(xml)
  File "/usr/share/virt-manager/virtManager/domain.py", line 729, in add_device
    raise RuntimeError, "Unable to attach device to live guest, libvirt reported
error:\n" + device_exception
RuntimeError: Unable to attach device to live guest, libvirt reported error:
virDomainAttachDevice() failed only CDROM disk devices can be attached
'

Created attachment 297593 [details]
Virt-manager logfile

When I try virsh dumpxml XP2, the response is:

error: failed to connect to hypervisor

It's a KVM guest.

This error is actually expected behavior. For a qemu/kvm guest, the only devices
that can actually be manipulated on a live guest are cdroms, and only for
connect or disconnecting an individual disk. The error message is certainly
unclear though, and virt-manager in general needs some better way to handle
attaching devices to live guests, either outright denying it or giving some
message like "This device will be available after the next reboot".

For dumpxml, try virsh --connect qemu:///system dumpxml XP2 (this issue will be
fixed in the next virt-manager release). However the xml isn't really neccessary
since it is in the log file you posted.

I'm still interest in comment #3, since that is an error I can't reproduce. My
guess is the device was disconnect from your machine when you tried to boot the
guest, the guest couldn't find the device and bombed, which is fine. But if you
can reproduce, please explain.

Re. https://bugzilla.redhat.com/show_bug.cgi?id=429485#c3 - yes, it's the guest
refusing to boot when the USB floppy drive is disconnected.

In this case I think your idea of a message indicating that a guest reboot is
necessary for the device to be available is a good idea.

Okay! I've finally fixed this upstream:

http://hg.et.redhat.com/virt/applications/virt-manager--devel?cs=935f3b243a91

If the guest is running and the user attempts to connect a device which is not hotpluggable, a warning will pop up saying something like "This change will only take affect on the next reboot". Error reporting and general interaction for this operations is a lot better as well.

Setting to POST.

Thanks,
Cole

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This stuff is a bit too invasive for F8, so moving this bug to F9. This will be fixed in the next update.

virt-manager-0.6.0-0.fc9 has been submitted as an update for Fedora 9.
http://admin.fedoraproject.org/updates/virt-manager-0.6.0-0.fc9

virt-manager-0.6.0-1.fc9 has been submitted as an update for Fedora 9.
http://admin.fedoraproject.org/updates/virt-manager-0.6.0-1.fc9

virt-manager-0.6.0-1.fc9 has been pushed to the Fedora 9 testing repository.  If problems still persist, please make note of it in this bug report.
 If you want to test the update, you can install it with 
 su -c 'yum --enablerepo=updates-testing-newkey update virt-manager'.  You can provide feedback for this update here: http://admin.fedoraproject.org/updates/F9/FEDORA-2008-10705

virt-manager-0.6.0-1.fc9 has been pushed to the Fedora 9 stable repository.  If problems still persist, please make note of it in this bug report.