[Qemu-devel] [Bug 1449687] Re: block migration of qcow2 VMs copies all empty space

[Anthony A.]

On the source :

# qemu-img info VM.img 
image: VM.img
file format: raw
virtual size: 20G (21474836480 bytes)
disk size: 3.4G

On the target:

# qemu-img info VM.img 
image: VM.img
file format: raw
virtual size: 20G (21474836480 bytes)
disk size: 20G


I also tried with qcow2 format but it's the same bug.

All kvm migration drop sparse disk image !

How can we resolve this ? 
Does a workaround exist ?

https://bugzilla.redhat.com/show_bug.cgi?id=1219541
https://bugzilla.redhat.com/show_bug.cgi?id=1248996
https://bugzilla.redhat.com/show_bug.cgi?id=1090093
https://bugzilla.redhat.com/show_bug.cgi?id=817700

** Bug watch added: Red Hat Bugzilla #1219541
   https://bugzilla.redhat.com/show_bug.cgi?id=1219541

** Bug watch added: Red Hat Bugzilla #1248996
   https://bugzilla.redhat.com/show_bug.cgi?id=1248996

** Bug watch added: Red Hat Bugzilla #1090093
   https://bugzilla.redhat.com/show_bug.cgi?id=1090093

** Bug watch added: Red Hat Bugzilla #817700
   https://bugzilla.redhat.com/show_bug.cgi?id=817700

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https://bugs.launchpad.net/bugs/1449687

Title:
  block migration of qcow2 VMs copies all empty space

Status in QEMU:
  New

Bug description:
  I'm running openstack 2012.1 'icehouse' which, ultimately, calls down
  into qemu-system-x86 2.0.0+dfsg-2ubuntu1.10.

  I primed the process by copying all necessary base images onto the
  destination host.  Nonetheless, post-migration instances are much
  larger than the original image; the copy duplicated all the empty
  space that ought to have remained copy-on-write.

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