We have a replicated mongo cluster (no sharding). On a member we have mongo running on a snapshot target device which is based on a DM encrypted device.
System: x86 server with Ubuntu 14.04 bare metal, mongo running inside a docker container, docker 1.9, mongodb 3.0.7 (3.0.4 shows the same issue), the mongo dbpath is bind mounted on the above mentioned snapshotting device (formatted with ext4).

The snapshot procedure consists of shutting down mongo with the proper command, followed by stopping and removal of the container.

In this stage the mongo.lock is empty but wired tiger lock is not. Restarting the member signals a file corruption but proceeds (I'm assuming because it's an RS). If I take the same snapshot and run a mongo standalone on it it will fail signaling that there are corrupted files (including often wiredtiger.wt).