Description of problem:

If I share a block device to use with multiple guests using w!, starting the
second guest via virt-manager throws trace back error and fails. Starting the
second guest via "xm create <guest2>" works fine without any problems.

Version of packages:

xen-3.0.3-41.el5
kernel-xen-2.6.18-53.1.4.el5
xen-libs-3.0.3-41.el5
xen-libs-3.0.3-41.el5
python-virtinst-0.103.0-3.el5_1.1
libvirt-0.2.3-9.el5
virt-manager-0.4.0-3.el5

How reproducible:

Always.

Steps to Reproduce:

- Create two para virtualized guests. I have not yet tested this with full virt.

- Create a block device. Either a logical volume or block device (sdax or hdax
etc..)

- Add the block device to both guests and add w! to make it shared.

Configuration file from both guests.

name = "guest1"
uuid = "de7b25c7-6f4c-26e0-af31-c2e07b05e3ed"
maxmem = 500
memory = 500
vcpus = 1
bootloader = "/usr/bin/pygrub"
on_poweroff = "destroy"
on_reboot = "restart"
on_crash = "restart"
vfb = [ "type=vnc,vncunused=1,keymap=en-us" ]
disk = [ "tap:aio:/vm/guest1.img,xvda,w", "phy:/dev/sda9,xvdb,w!"]
vif = [ "mac=00:16:3e:47:aa:a4,bridge=xenbr0" ]


name = "guest2"
uuid = "8493c330-f15d-4b33-9909-16a210b83fd9"
maxmem = 500
memory = 500
vcpus = 1
bootloader = "/usr/bin/pygrub"
on_poweroff = "destroy"
on_reboot = "restart"
on_crash = "restart"
vfb = [ "type=vnc,vncunused=1,keymap=en-us" ]
disk = [ "tap:aio:/vm/guest2.img,xvda,w", "phy:/dev/sda9,xvdb,w!" ]
vif = [ "mac=00:16:3e:47:aa:a5,bridge=xenbr0" ]

- Start the guest1 from virt-manager. It would start successfully.

- Then start the second guest from virt-manager. You would see the below error
message.

libvir: Xen Daemon error : POST operation failed: (xend.err 'Device 51728 (vbd)
could not be connected.nDevice /dev/sda9 is mounted in a guest domain,nand so
cannot be mounted now.')
Traceback (most recent call last):
 File "/usr/share/virt-manager/virtManager/manager.py", line 693, in start_vm
   vm.startup()
 File "/usr/share/virt-manager/virtManager/domain.py", line 375, in startup
   self.vm.create()
 File "/usr/lib64/python2.4/site-packages/libvirt.py", line 217, in create
   if ret == -1: raise libvirtError ('virDomainCreate() failed', dom=self)
libvirt.libvirtError: virDomainCreate() failed POST operation failed: (xend.err
'Device 51728 (vbd) could not be connected.nDevice /dev/sda9 is mounted in a
guest domain,nand so cannot be mounted now.')

Actual results:

Second guest start up fails through virt-manager.

Expected results:

Second guest start up should be successful via-virt manager.

Additional info:

If we start the second guest via "xm create guest2" it starts successfully and
attaches the shared block device without any problems to the second guest.

[root@dhcp6-7 xen]# xm create guest2
Using config file "./guest2".
Started domain guest2


- If you use a file backed image and share them between two guests using w!
flag, we can stat both guests from virt-manager without any prorblems. Problem
seems to be only while sharing block device.

--

Please note this is fixed in libvirt 0.3.3.5.el5