That was a straw man (sorry). There's also the overhead of maintaining consistency, synchronizing metadata, etc. I don't think assuming 0.1% CPU overhead for

That was a straw man (sorry). There's also the overhead of maintaining consistency, synchronizing metadata, etc. I don't think assuming 0.1% CPU overhead for Lustre is a terrible estimate, but even if it were much lower, the argument would still hold (at least at the scale of Titan).