[Libguestfs] virt-v2v stuck EDAC sbridge

[Richard W.M. Jones]

On Mon, Sep 11, 2017 at 06:38:14PM +0000, Seth Tanner wrote:
> The virt-v2v machine is running inside openstack, so there is nested
> virtualization. To the best of my understanding all of the
> appropriate flags have been set to support nested virtualization.

Ah OK, it's likely to be a bug in nested virt.  Unfortunately nested
virt is a bit of a minefield, and often has bugs.  Also the bugs tend
to depend on the exact CPU vendor and model.

...
> >You could also try running without using KVM.  It'll be a bit slower
> >but is usually less buggy than nested virt:
> 
> >  export LIBGUESTFS_BACKEND_SETTINGS=force_tcg
> 
> If the backend is set to direct, it hangs at image conversion

> libguestfs: trace: disk_create "/var/tmp/glance.hzY7jr/sda" "raw" 42949672960 "preallocation:sparse"
> libguestfs: trace: disk_create = 0
> qemu-img 'convert' '-p' '-n' '-f' 'qcow2' '-O' 'raw' '/var/tmp/v2vovle834c2.qcow2' '/var/tmp/glance.hzY7jr/sda'

Assuming that it hasn't run out of space on /var/tmp, it's probably
doing stuff here, just slowly or lumpily.  Since qemu-img creates
sparseness, not writing to the output file (for short-ish periods) is
expected, since it will be skipping over holes.

You might want to attach strace to qemu-img and see if it is making
system calls.

> If the backend is set to libvirt 
> It hangs inspecting the overlay
...
> libguestfs: trace: v2v: mount_ro "/dev/sda1" "/"
> guestfsd: main_loop: proc 395 (is_whole_device) took 0.09 seconds
> guestfsd: main_loop: new request, len 0x40
> commandrvf: stdout=n stderr=y flags=0x0
> commandrvf: udevadm --debug settle -E /dev/sda1
> calling: settle
> commandrvf: stdout=n stderr=y flags=0x0
> commandrvf: mount -o ro /dev/sda1 /sysroot/

It's pretty unlikely that there would be a difference here between
direct & libvirt backends.  Could it be slow?  Could /var/tmp be
running out of space?  See also this old (but still current) bug:

https://bugzilla.redhat.com/show_bug.cgi?id=745576

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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