Given all of the scale-out/scale-up flexibility that NetApp provides, customers sometime have difficulty deciding whether to use cDOT clusters built of fewer nodes with higher-end storage or more nodes with mid-range storage systems. As the paper shows, data centers are better served with clusters that contain more nodes of mid-range storage than an equivalent capacity configured with fewer cluster nodes of higher-end storage or dual controller scale-up systems from other vendors.
Figure 1 - multi-node cluster
A similarly equipped four-node cDOT cluster - leveraging either FAS or AFF nodes, or both - has more utilization flexibility, added resiliency and better FlexArray virtualization adaptability than a two-node cDOT cluster or other vendors’ dual controller scale-up systems. IO performance and application isolation advantages also come with using a four-node over a two-node cDOT cluster. As the author states, the case is clear: purchasing a four-node cDOT cluster makes much more sense than a two-node cluster or traditional, scale-up, dual controller storage systems.