> If you're doing a 20+ disk array ...
Then you might want to consider ceph.
Then you might want to consider ceph.
If you're comfortable with the node being a single point of failure, you can do a lot with a single storage node connected to a JBOD and serving data over NFS. And even if the node is the unit of failure, you can attach a SAS JBOD to multiple servers if you'd like.
In my position, in addition to the added cost, I just don't have the physical rack space for the extra servers required for ceph.
Sure, it depends but the 140 drives (mentioned by secabeen) alone will take up a huge amount of space. Maybe I just wanted to point out that there might be a point when you have maxed out the storage capability of a single node and might want to consider a distributed storage setup.