Comment 0 for bug 1327497

I tried live-migration against VM with multipath access to FC bootable volume and FC data volume.
After checking the code, I found the reason is that
1. /dev/dm-<NUM> is used, which is subject to change in the destination Compute Node since it is not unique across nodes
2. multipath_id in connnection_info is not maintained properly and may be lost during connection refreshing

The fix would be
1. Like iSCSI multipath, use /dev/mapper/<multipath_id> instead of /dev/dm-<NUM>
2. Since multipath_id is unique for a volume no matter where is is attached, add logic to preserve this information.