The conversion fails when the /var directory is cloned.
To isolate the cause of this issue:
Check these logs on the source physical machine to see if there is any indication why the tar failed:
/var/log/messages
/var/log/warn
Check the output of the dmesg command to see if there is any indication why the tar failed.
Do a test of tarring /var to another system (this is what happens in the helper virtual machine during conversion).From the other system that is simulating the actions of the helper virtual machine, run the commands:
# mkdir -p /tmp/p2v-src-root/var (assuming you have enough space in /tmp for the contents of /var from the source)
If Step 3 fails, try to determine which files were not cloned by doing a binary search of the/var tree on the source and /tmp/p2v-src-root on the destination. du -sh /var/foo tells you the size of each directory, so you can compare directory sizes until you find directories that differ in size.