Collective I/O Implementations
Global Barrier : barrier synchronize at the outset, then perform non-collective call.
Node Grouping : nodes making I/O requests are partitioned into groups, then take turns executing I/O.
Two-Phase I/O : I/O requests are first permuted according to a conforming distribution. After permuting, I/O is performed.
Disk-Directed I/O : One cnode sends the collective request to all I/O nodes. I/O nodes optimize, perform requests, and sends data directly back to the cnodes.