
56 High Performance Parallel I/O
FIGURE 5.1 (See color insert): A pictorial representation of the hardware
packaging hierarchy of the BG/Q scaling architecture. The smallest configu-
ration could be a portion of a midplane and a single I/O card. The Sequoia
system is composed of 96 racks each with one I/O drawer containing eight
I/O cards (768 I/O nodes total).
a full Red Hat Enterprise Linux-based kernel (the Lustre client software is
run at this level). Compute nodes are connected to other compute nodes by
the 5D torus network; but I/O nodes perform all I/O requests on behalf of
compute nodes. These compute nodes “function ship” I/O requests to their ...