Bug 1015175

Description of problem:
Migration of a VM from 3.3 host to 3.2 host fails. Libvirt throws an exception that it cannot find the VM disk image file on the target host under /var/run/vdsm/storage/ directory, which is missing there completely.
Note: SELinux was set to permissive mode on both hosts.

Version-Release number of selected component (if applicable):
3.3 host:
vdsm-4.12.0-156.git6e499d6.el6ev.x86_64
libvirt-0.10.2-27.el6.x86_64
qemu-kvm-rhev-0.12.1.2-2.355.el6_4.7.x86_64

3.2 host:
vdsm-4.10.2-25.1.el6ev.x86_64
libvirt-0.10.2-18.el6_4.14.x86_64
qemu-kvm-rhev-0.12.1.2-2.355.el6_4.2.x86_64


How reproducible:
100%

Steps to Reproduce:
1. Add 3.3 and 3.2 host in a 3.2 cluster.
2. Create new VM with a bootable disk and run it on the 3.3 host.
3. Migrate the VM to the 3.2 host.

Actual results:
Migration fails - webadmin message: "Migration failed due to Error: Fatal error during migration (VM: win7x64, Source: srh-09, Destination: srh-10).".
Target host's libvirtd.log: virFileOpenAs:1073 : failed to open file  '/var/run/vdsm/storage/84f6d841-6c6a-49be-a0f5-b7d80f876573/1985711b-46fd-4cb7-909b-1168f60b5547/548c7b86-b75e-441e-97b9-c163ffdacaca': No such file or directory.

Expected results:
Migration completes successfully.

Additional info:

The file exists on the source host:
# ls -lh /var/run/vdsm/storage/84f6d841-6c6a-49be-a0f5-b7d80f876573/1985711b-46fd-4cb7-909b-1168f60b5547/548c7b86-b75e-441e-97b9-c163ffdacaca
-rw-rw----. 1 vdsm kvm 1,0G  2. říj 13.41 /var/run/vdsm/storage/84f6d841-6c6a-49be-a0f5-b7d80f876573/1985711b-46fd-4cb7-909b-1168f60b5547/548c7b86-b75e-441e-97b9-c163ffdacaca

But on the target host...:
# ls /var/run/vdsm/storage
ls: cannot access /var/run/vdsm/storage: No such file or directory