Emerging Storage Paradigms

Driven by coincidental booms in the Internet, intranets and data warehousing, IT organizations are amassing ever larger stores of data. A recent study by the National Storage Industry Consortium (San Diego, www.nsic.com) found that the amount of data stored on the world’s networks will reach 1,000 petabytes (1 million TB) by 1999. In addition, a recent survey by market research firm and consultancy the Business Research Group (Newton, Mass., www.bgresearch.com) indicates that 75 percent of IT managers acknowledge that storage management is becoming a critical component of their strategic high-availability development plans. To provide IT managers with the tools and resources to effectively distribute and manage data, storage vendors are pushing solutions based on both network-attached storage (NAS) and storage-area network (SAN) paradigms.

"NAS and SAN will grow in both absolute and market share measurements," writes Robert Gray, a research analyst with International Data Corp. (IDC, Framingham, Mass., www.idc.com) in an IDC white paper titled "Distinquishing Network-Attached Storage From Storage Networks."

Both NAS and SAN leverage new high-performance Fibre Channel technology and are ostensibly concerned with distributing storage resources in a network-centric paradigm, although each technology approaches such goals from a decidedly different strategy. In a SAN, writes IDC’s Gray, "storage is uncoupled from dependence on network servers and communications protocols, and consolidated and managed as an independent resource." The effect is to allow storage devices to transparently communicate directly with any server or desktop on the network or even with other storage devices.

NAS is popularly defined as a network-centric concept that provides shared storage. "In contrast to the SAN paradigm, [NAS] is distinguished by the network being located between the application server and the file system," writes IDC’s Gray. "NAS products attach directly to LANs and communicate using NFS, CIFS, FTP, HTTP, and other networking protocols."

But what of the actual differentiation between NAS and SAN in terms of practical, real-world implementations? According to Erik Norlander, director of marketing with the network systems group of storage vendor Storage Technology Corp. (StorageTek, Louisville, Colo., www.storagetek.com), both paradigms can be clearly differentiated in terms of a traditional tier model, with SANs seeing greater deployment in high-end implementations and NAS solutions emerging as popular in middle-tier and low-end implementations.

"The most predominant application that you’re going to see SANs deployed for initially is for backup in large data environments, so you’re talking about data warehousing and Web serving," Norlander says. He notes that as more and more organizations move to 24x7 operations, backup becomes more important even as the windows of opportunity to perform backup become nonexistent.

Fibre Channel will be the primary enabling technology for SANs, maintains Jeff Vogel, vice president of marketing and business relations with Fibre Channel hub and switch vendor Vixel Corp. (Bothell, Wash., www.vixel.com). "Fibre Channel is a standard, and users don’t buy things that aren’t based on standards," he argues. "In addition, it does solve some very real problems, such as scalability, connectivity, flexibility distance and performance."

Fibre Channel’s performance and scalability characteristics are ideal for the rigors of the data center, Vogel claims. Such is in keeping with the projection of IDC’s Gray, who believes that SANs will evolve to support data center management, eventually becoming "a core enterprise concept used in both data centers and 'location' centers as the structure for managing enterprise data assets."

In contrast to the SAN paradigm, explains StorageTek’s Norlander, most NAS deployments will be in the client/server arena where clients are directly accessing and manipulating files that are controlled by traditional file systems. NAS implementations need not leverage Fibre Channel to the extent that SAN implementations likely will, and will, conversely, probably embrace a wide variety of low-end devices.

"What we’re doing is bringing the network and storage together," explains John Eckstein, director of Japanese OEM sales with Creative Design Solutions Inc. (CDS, Santa Clara, Calif., www.creativedesign.com). CDS manufactures the Plug and Stor line of products, thin servers that provide plug-and-play NAS functionality for printers, disk drives and CD-ROM drives, as well as for emerging storage devices such as the Zip and Jaz drives available from Iomega Corp. (Roy, Utah, www.iomega.com).

IDC's Gray predicts that "NAS will grow to provide ease of use in small networks and will find applications in the form of data caches, as disk capacity compensates for the higher cost of network bandwidth."