your servers are just as unavailable either way Right, but having local disks reduces the sources of failure, reduces contention, reduces latency, reduces the

your servers are just as unavailable either way Right, but having local disks reduces the sources of failure, reduces contention, reduces latency, reduces the complexity of failures, and is thus much nicer to work with. Computers and networks would be easier for us to debug if they had a binary works well/doesn't work at all, but we all know they don't. Especially networks. The simplest and sanest architecture is keeping dumb disks local to where computation is running (and yes, that may also include duplicating data across several servers). Anything else is asking for more crazy classes of failure. Been there, bled there, not going back there.