Convergence or Collision?

The capability gap between SAN and NAS gets smaller as each technology continues to evolve. At first glance, this convergence might look as if it will leave IT managers with difficult long-term decisions about where they should store their data.

eWeek Labs continuing analysis of storage area network and network-attached storage products and standards leads us to believe SAN/NAS convergence will provide revolutionary storage and performance gains, and the evolution of storage virtualization and high-speed networking will eventually eliminate the need to choose between the two.

To take the industrys pulse on where SAN and NAS implementations currently fit in the infrastructure plans of storage heavyweights, eWeek Labs spoke recently with representatives from EMC Corp., IBM, Network Appliances Inc., Storage Technology Corp. and Sun Microsystems Inc. Although they generally agreed on the advantages and disadvantages of each technology, their views differed somewhat as to where they would place each scheme in their current and future storage strategies.

The experts said they believe that SAN and NAS are currently complementary technologies, with NAS well-suited for file sharing services and SAN a good method for centralizing storage and providing high-speed storage for application servers.

"We dont believe there is a battle between NAS and SAN," said James Staten, director of strategy for the Network Storage Division at Sun, in Palo Alto, Calif.

"SAN is a networking technology for data centers that allows the sharing of storage resources and centralization for easier management. NAS is a class of server designed to provide simple file sharing. Both have their place in the market and in the same customer environment," Staten said.

For SANs, the biggest negatives are the additional infrastructure required (for example, setting up a Fibre Channel network), the long learning curve necessary for mastery of the technology and the less-than-stellar interoperability of Fibre Channel components, according to the experts.

Unlike NAS products, which can usually speak to servers using protocols such as Network File System, Common Internet File System and Apple-Talk, SAN products have no file serving interoperability out of the box.

Randy Chalfant, director of corporate strategy at Storage Technology, in Louisville, Colo., put it this way: "Today, SANs provide shared storage to a cluster of homogeneous servers only, with shared storage of heterogeneous servers a key potential of future SANs."

Expanding SANs

As new technologies such as storage virtualization and advanced storage management come into play, more IT managers will be willing to extend their SANs to heterogeneous platforms. Participants listed several advantages to doing so, including SANs high performance, scalability and redundancy when designed with multipathing capabilities (the ability to redirect network traffic to another path in the event of a hardware failure).

With the emergence of 2G-bps Fibre Channel, Fibre Channel-based SANs are now faster than current Gigabit Ethernet technologies. However, the impending release of 10G-bps Ethernet will push IP network bandwidth far beyond that of Fibre Channel, and it may give NAS vendors, which use IP for networking, a fast connection from clients to NAS units. (For more about eWeek Labs take on 10G-bps Ethernet, go to www.eweek.com/links.)

Most of the interview participants believe that the main advantages of NAS technology are ease of use, the ability to access remote data over standard IP networks, excellent out-of-the-box interoperability and its cost-effectiveness across enterprises of every size.

On the negative side, Chuck Hollis, EMCs vice president of markets and products, in Hopkinton, Mass., said performance is a potential problem for NAS schemes. Hollis also said that a NAS configuration could potentially weaken security between applications and storage because NAS uses IP, so it can potentially be sniffed and compromised by IP-based hacker tools. In addition, performance doubts make it difficult to implement large or high-throughput database implementations on NAS, he said.

As Hollis stated, it has traditionally been a given that NAS products are too slow to run as the storage back end for application servers at most organizations. Now its time to see for ourselves if the performance gap is really a big issue.

eWeek Labs is working on application-based benchmark tests that will test enterprise-class NAS systems to determine whether the performance gap between SAN and NAS is still wide, or if advances in NAS hardware and software capabilities (such as communication protocols and file systems) have closed it enough for NAS to be a viable data repository for applications such as e-mail and databases.

Senior Analyst Henry Baltazar can be contacted at henry_baltazar@ziffdavis.com.