Effect of Cluster Size

By itself, the size of a cluster (number of nodes) does not favor either colocating or not colocating applications and PFS I/O daemons. Larger clusters do, however, attenuate the benefits of colocating. This is because the amount by which colocating reduces network traffic can be expressed as

    T_c = T_s - T_s/N

where T_c is the level of network traffic using colocating, T_s is the level of network traffic without colocating, and N is the number of nodes in the cluster. In other words, colocating reduces network traffic by 1/number-of-nodes. The more nodes there are in the cluster, the smaller the effect of colocating.