libvirt users - Jan 2017 - Re: Libvirt 3.0 machine start fails on LVM

Hello,

Since updating to libvirt 3.0 I am no longer able to create a virtual
machine that is backed by LVM storage on my two Arch machines.

This is the error in virt-manager:

Unable to complete install: 'An error occurred, but the cause is
unknown'

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 88, in
cb_wrapper
    callback(asyncjob, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/create.py", line 2288, in
_do_async_install
    guest.start_install(meter=meter)
  File "/usr/share/virt-manager/virtinst/guest.py", line 461, in
start_install
    doboot, transient)
  File "/usr/share/virt-manager/virtinst/guest.py", line 396, in
_create_guest
    self.domain = self.conn.createXML(install_xml or final_xml, 0)
  File "/usr/lib/python2.7/site-packages/libvirt.py", line 3773, in
createXML
    if ret is None:raise libvirtError('virDomainCreateXML() failed',
conn=self)
libvirtError: An error occurred, but the cause is unknown

I originally encountered the problem when running my Ansible modules
for libvirt in https://github.com/ansible-provisioning/ansible-provisioning
, so the issue is not virt-manager specific.

Steps to reproduce in virt-manager (1.4.0-3):
- create a new VM
- choose import existing disk image
- create a new logical volume when browsing to find the existing image
path or select a lv that was manually created before.
- click forward
- click forward
- click finish

When using qcow2 storage, both virt-manager and my modules work fine.
This was also working on previous versions of libvirt. I do not see
any changes in compilation flags in the Arch packages.

Is there anything I can do to help diagnose this issue?

Greetings,

Jeroen

On 01/26/2017 09:07 PM, Jeroen Hoekx wrote:
> Hello,
> 
> Since updating to libvirt 3.0 I am no longer able to create a virtual
> machine that is backed by LVM storage on my two Arch machines.
> 
> This is the error in virt-manager:
> 
> Unable to complete install: 'An error occurred, but the cause is
unknown'
This is likely a namespace bug. There are patches on the list to fix the
issue [1], but lacking any review. Can you try applying them and see
whether they fix your problem?

1: https://www.redhat.com/archives/libvir-list/2017-January/msg01127.html

Michal

On 31 January 2017 at 13:07, Michal Privoznik <mprivozn@redhat.com>
wrote:
> On 01/26/2017 09:07 PM, Jeroen Hoekx wrote:
>> Since updating to libvirt 3.0 I am no longer able to create a virtual
>> machine that is backed by LVM storage on my two Arch machines.
>>
>> This is the error in virt-manager:
>>
>> Unable to complete install: 'An error occurred, but the cause is
unknown'
>
> This is likely a namespace bug. There are patches on the list to fix the
> issue [1], but lacking any review. Can you try applying them and see
> whether they fix your problem?
>
> 1: https://www.redhat.com/archives/libvir-list/2017-January/msg01127.html
After applying these patches I could indeed create a VM on LVM storage again.

Thanks,

Jeroen