[Libguestfs] Virt-v2v conversion issue

Richard W.M. Jones rjones at redhat.com
Tue Oct 14 06:44:00 UTC 2014

The ioctl failure is not an error, but it's unexpected, and maybe
hints at something deeper.

What version of libguestfs-winsupport is installed?  It should be
7.1-3.el7 (assuming this is RHEL 7), which has support for fstrim of
aligned NTFS partitions.

- - -

Now on to the real problem ... 'qemu-img convert' is running, and then
fails.  Does it hang or crash?  I would enable core dumps and capture
one, since there's obviously a bug in qemu-img:

(1) As root do:

  echo core.%p > /proc/sys/kernel/core_pattern

(2) Before running virt-v2v, do:

  ulimited -c unlimited

and you should get a core.* file in the current directory when
qemu-img segfaults.  Attach that file to gdb to get a stack trace:

  gdb /usr/bin/qemu-img core.XYZ
  (gdb) t a a bt

It's very unexpected for qemu-img convert to fail, especially from a
raw format local disk.  But bugs can happen ...

If qemu-img is hanging, not crashing, then you can attach gdb directly
to the process and get a stack trace that way.

What version of qemu-kvm-rhev is this?

- - -

If fstrim is successful then it should greatly reduce the amount of
data to copy, both saving you lots of time and making the 'qemu-img
convert' bug harder to hit.


Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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