Network Attached Storage Versus Storage Area Networks

by Chris Connor

Overview

Although some of the differences of Network Attached Storage (NAS) and Storage Area Networks (SANs) have been discussed several times in this series thus far, a full, blow by blow analysis of these two rapidly growing storage technologies is warranted.  First, lets start with the basics.  SANs are simply storage devices and servers connected together the way that computers are connected on Local Area Networks or LANs.  A SAN uses fibre channel as its backbone while Ethernet usually serves as the backbone for LANs. On the other hand,  Network Attached Storage connects to the network instead of having a separate network devoted solely to storage.  An NAS appliance is not tied to a server like SANs are because it acts like a server itself - as an appliance linked to a network by an Ethernet card.  This appliance usually consists of a group of hard disk drives, a processor, and its own operating system. 

Ethernet Versus Fibre Channel

When comparing NAS and SANs, it is extremely important to the know the differences between Ethernet and fibre channel.  Fibre channel is specifically targeted toward storage, while Ethernet is much more widely available as a network standard.  Because it is a specialized technology, fibre channel makes SANs much harder to install and maintain than a simple network attached storage appliance.  Only IT professionals with knowledge of both storage and networks should install and maintain SANs.  However, that is not usually what happens.  Most of the time, SANs are the responsibility of system administrators who are usually familiar with storage but not networks.  On the other side, an NAS appliance simply acts like any other server on the network and is installed only with a web browser and installation wizard. 

The one advantage that fibre channel currently gives SANs over NAS is performance.  Because fibre channel is dedicated to storage, it currently offers higher speed than an NAS on an Ethernet network - since there are various other types of traffic on the network.  The presence of these various types of traffic on a network is the reason that storage has been directly powered by a server instead of resting on a network the way an NAS appliance does.  However, increasing bandwidth is changing all of that.  Soon, Ethernet will likely pass fibre channel in performance as companies such as Cisco {CSCO} and Lucent {LU} are working on improving Ethernet speeds.  Already, these two giants have created the fastest Ethernet so far - 10 gigabit Ethernet. 

The Stocks

In terms of the sheer number of stocks with significant investment potential, the SAN market wins over NAS, hands down.  The SAN market boasts several companies with investment potential while NAS has only one, Network Appliance {NTAP}.  The SAN market consists of several components such as managed hubs, routers, adapters, and switches.  There is usually one company that dominates the market for each SAN component - like Gadzoox {ZOOX} with managed hubs, Crossroads {CRDS} with storage routers, and Brocade {BRCD} with fibre channel switches.  In addition, several SAN companies that make fibre channel adapters show investment potential - including Emulex {EMLX}, JNI {JNIC} and Qlogic {QLGC}. 

However, some investors may prefer a single company that dominates its market the way that Network Appliance does in NAS.  Network Appliance dominates NAS because of superior technology like its Write Anywhere File Layout (WAFL) system.   WAFL enables efficient data storage of heterogeneous file formats from various environments such as Windows NT, Unix, and the Web.  In fact, WAFL is the closest thing to true data sharing that NAS offers.  The only way for true data sharing to become a reality would be if only one operating system were used - and that will likely never happen. 

Conclusion