We had an incident couple weeks ago. A faulty node in a Windows 2008 R2 Hyper-V cluster caused the partition table lost in one of the CSV. Consequently, all the data can not be accessed.
I mounted the broken CSV LUN to another host with TestDisk installed. Then I used TestDisk to search and fix the broken partition table. After that, I mounted it back to the cluster. All data is back!! whew~
Here is the TestDisk step by step instruction. Easy but very useful!