We have several disk arrays that are shared in a distributed file system across multiple servers using GlusterFS. It works really well.
The problem is, we have no available storage that is not appropriated to the distributed file system. As a result, I have stored our MongoDB data within the distributed file system.
For now, I have no benchmarks for performance considering it is the only available solution for my setup. However, I've been thinking of dedicating a disk array and server to only mongo, where I would plug the disk array directly into the server.
Does anyone know why you should, or should not store mongo data on top of distributed file system? I know Mongo has it's own sharding solution for precisely this reason, so I'm thinking that it's not ideal. If you have multiple blocks of data that mongo thinks are in the same location, however they are actually on different storage media, can this cause a performance issue?