I have not looked at Lustre, as I have heard many negative things about it (including Oracle ownership). The only business using Lustre where I know the admins has had a lot of trouble with it. No redundancy.
I know some Lustre admins that indeed have the far away stare similar to people that have survived natural disasters. It can be somewhat unstable and difficult to manage when you try and roll it yourself but, if you get the professionals and have it properly supported you can have a good time.
Lustre is not owned by Oracle, its free and opensource software Licensed under GPL v2. It does have redundancy but this is handled on the hardware level with Active / Active object storage servers and meta data servers.
Primarily supported by Intel. Well, they have the most developers and sell the most support contracts. It is a very interesting replacement for Hadoop HDFS.
Fhgfs looks interesting, and I am planning on looking at it, but have not yet done so.
The Fraunhofer Parallel Cluster File System (FhGFS) has just been spun out of the German Institute from which is was born and has been renamed BeeGFS. (the germans never had a knack for snappy names :).
It is a very strong contender for these kinds of workloads and is probably just about to be fully opensourced.
In general Parallel filesystems such as Lustre are quite hard to get right and most people fail to grasp the complexity and the skill required in implementing them. People have a go, fsck it up (heh) and then blame the software when it doesn't work properly. If you really have a business requirement for insane metadata performance over single, multi petabyte namespace you should be sure to tread lightly and carry a good support contract.
MooseFS and GlusterFS have both been evaluated, and were too slow. In the case of GlusterFS, waaaay too slow.
I believe Gluster to be a rapidly dying project however I am willing to be set straight on this point. It seems that anyone looking at Gluster will also be looking a Ceph and this is an obviously better system.