Enterprise systems with scale-out capability have been making an impact in IT environments and are almost always a consideration in every evaluation of client storage strategies.
Although there are scale-out implementations of block and object storage, NAS has been the primary focus for enterprise scale-out storage deployments. Scale-out products range from the enterprise down to the SMB market. Some high-end scale-out NAS systems such as EMC Isilon and Hitachi Data Systems HNAS have made a transition from high performance computing (HPC) to enterprise IT.
Benefits of using scale-out NAS include:
• Performance scales in parallel with capacity so increases in capacity do not cause performance impacts requiring additional administrative effort to diagnose and correct.
• The continued increase in unstructured data can be addressed without a single administrative system without increasing administrative efforts and costs.
• New technology elements can be introduced and older ones retired without having to offload and reload data.
Not all NAS systems offered today are scale out. Traditional dual-node controller NAS systems still fit many customer needs, and are usually kept as separate platforms than scale-out systems. It is easier to design a new scale-out NAS system than to adapt an existing design and maintain the high-value features, although NetApp has shown that new technology can be introduced and adapted with its Clustered Data ONTAP systems.
A common approach to scale-out NAS is to take a distributed file system used in HPC and research environments. Considering the success vendors are having with their scale-out NAS offerings, it would seem to be inevitable that a majority of enterprise NAS systems will be multi-node, scale-out systems.
Vendors have several terms for scale-out NAS and scale-out storage in general. A look at some of the vendor product offering sees the terms clustered NAS, federated systems, and distributed systems. These are mostly vendor marketing aimed at creating a unique identification for their products. They are more likely to create confusion.
While scale-out block storage may be more difficult to implement because of the host interface connection and greater latency demands than NAS, the implementations provide the same value to IT customers. The measure is the number of nodes in the system and how the nodes are organized such as in pairs or an N+1 protection arrangement.
Scale-out NAS and scale-out storage in general is becoming prevalent because of the value. Vendors will continue to develop products that meet customer needs and more scale-out systems should be expected.
(Randy Kerns is Senior Strategist at Evaluator Group, an IT analyst firm).