If not someone forces you to use it, I would also highly recommend using anything else than Lustre. From what I hear from others and what also gave myself nightmares for quite some time is the fact that Lustre quite easily breaks down in all kinds of situations. And if only a single client in the system breaks down, it puts itself into an endless do_nothing_loop mode typically while holding some important global lock - so the next time another client tries to access the same information, it will also hang. Thus, you often end up rebooting the whole cluster, which I guess is something you would try to avoid normally ;)
Modern parallel file systems like FhGFS (http://www.fhgfs.com) are way more robust here and also allow you to do nice things like running server and client components on the same machines (though built-in HA features are still under development, as someone from their team told me, but their implementation is going to be pretty awesome from what I've heard).
