NAS Offers a Gateway to the SAN World
Even as the NAS market slows, NAS gateways are expected to keep growing at a healthy pace, as users make the most of existing SAN infrastructures. NAS gateways offer flexibility and scalability and better utilization of storage resources, as well as a single point of management for both NAS and SAN, but they're also gaining favor because of greater use of heterogeneous SAN storage arrays.
Eric Schott, EqualLogic's director of product management, said he is seeing strong demand for NAS gateway products.
"NAS gateways provide an efficient method to provide and grow NAS services while maintaining consolidated storage," said Schott. "They also allow for choice in NAS services, allowing the best service based on features and client integration to be provided."
This allows for changes in NAS services over time updated protocols, clustered gateways, clustered file systems and the like and helps keep NAS services, operations and upgrades independent from SAN operations, he said.
The best example of the continuing growth of NAS gateways, according to Stephen Harding, director of marketing at Tek-Tools Software, is IBM's success with its N Series, an OEM version of NetApp's products. "This is not a new idea in the marketplace," said Harding. "EMC Celerra NAS heads have been capitalizing on the Clariion/Symmetrix/DMX back end for many years now."
NAS has a couple of big management benefits over SAN, according to Jim McDonald, chief technology officer of WysDM Software. One is that NAS has lower performance requirements than SAN, at least in the eyes of end users, and another is that usage of NAS is much clearer than usage of SAN, by virtue of the NAS head being able to provide metrics directly rather than through the client (and often the client's applications such as the database).
McDonald believes that as existing SAN infrastructure ages, it is more likely to be converted to NAS than junked. "Management of NAS is still significantly easier than SAN, mainly because it works at the same level as end users think," the file system level as opposed to the raw disk level, he said.
When Storage Worlds Collide
NAS and SAN have been moving closer together as complementary technologies, since there is no one-size-fits-all hybrid yet, and NAS gateways allow firms to use storage networks for both block and file-based traffic.
However, unlike unified storage, industry experts expect the management of NAS gateways to continue to be separate from the management of SAN arrays because they typically are based on different platforms. Also, NAS is more of a device-oriented strategy, while SANs are more a method of providing storage.
"There is no management solution between different NAS gateways, and there is no management solution between different SAN arrays, so the chance of getting something that covers both is remote at best," said McDonald. "For all of the talk of standards, these guys are all competing, and software sales are a key way of keeping up their margins, as it is a real value-add and not something that can be provided by the competition. I don't see that going away any time soon."
"Regardless of the platforms they are based on, how you manage NAS file systems and SANs are fundamentally different one deals with servers and file systems, the other deals with hosts and arrays," said Pete Lavache, EMC's director of storage product marketing, who notes that EMC was the first company to market with a NAS gateway. "These are not only different tasks, they are often managed by different organizations within the same company."
Schott said NAS administrators deal with issues like user authentication and authorizations, file quotas, sharing permissions, user-based file recovery, single-instance storage and archiving of data, tasks that don't exist in SANs. But he noted that operating NAS gateways with a SAN doesn't increase management, since NAS management needs to be done anyway.
"Typically, NAS services are connected to client networks, where SAN services are not," said Schott. "It is common that a unified device could be harder to manage the challenge in management is not only the number of devices, but the complexity and connectivity of the devices."
Harding takes a minority view on the issue of NAS gateway and SAN management. "Since the business driver for NAS gateways is to capitalize on existing SAN infrastructures, I anticipate customers demanding management from a single interface," said Harding.
He said one of the key goals in developing Tek-Tools' reporting and monitoring tools was a single interface to view all parts of the infrastructure. Management will likely need to follow the same path, he said.