Network Computingwww.networkcomputing.com

With the ability to support file serving in a heterogeneous environment, a NAS (network-attached storage) server is the first step to ending some of that anguish. Offering superior scalability, simple setup and administration, cross-platform support, security integration, and an extremely low TCO (total cost of ownership), NAS servers are beginning to prove just how valuable they are.

If your organization is feeling the stress of growing storage requirements, planning storage capacity or looking for a way to simplify content delivery in a heterogeneous or a homogeneous network, the evaluation of NAS servers is a must.

NAS servers' sheer versatility sets them apart from conventional file servers. You'll have to get past one big obstacle, however: the preliminary comparison between a NAS server and an off-the-shelf Windows NT or a NetWare file server. Many IT managers may base their decisions on this initial price/performance factor, in which case midrange NAS servers are generally at a disadvantage.

We tested NAS servers from Excel/Meridian Data, JES Hardware Solutions, Land-5 Corp., Network Appliance, Network Storage Solutions and Procom Technology. If we had based our decisions solely on the initial price/performance, our evaluation would have ended early. We ran performance tests against a Dell Computer Corp. PowerEdge 4400 server with a Windows 2000 server, which at around $12,000 costs a third as much as--but outperformed most of--the NAS servers we tested.

In anything other than a small, homogeneous workgroup environment, however, it wouldn't take long for the TCO of that Dell server to fly past that of the NAS server. In fact, a recent study done by the Gartner Group found that at least 50 percent of a server's expenses could be traced directly to storage. The same study also found that organizations that implemented NAS servers to scale their storage requirements have reduced storage costs by up to 88 percent.

Scalability is certainly an important feature of midrange and high-end NAS servers. Although SCSI is still a popular option, a number of NAS servers are using Fibre Channel interfaces to enhance the scalability of back-end storage. This was the case with the Land-5 and Network Appliance servers, which enabled the Land-5 Icebox solution to scale up to 10 TB. In its current configuration, our Dell server was capable of supporting only 180 GB.

Adding storage to the NAS servers is a plug-and-chug affair that doesn't require the administrator to have any advanced knowledge of SCSI or Fibre Channel technologies. Additionally, as we found with Network Appliance's NetApp F720 File Server, it takes only minutes to bring the additional storage online. To achieve the same scalability results with our reference Dell server, an administrator would need to have advanced knowledge of storage architecture. The setup would require a number of SCSI or Fibre Channel RAID adapters to be certified and configured in the NOS. And during the longer time taken to add storage to a typical NT server--sometimes two or three days--that server must be completely offline.

When compared with a general-purpose file server such as our Dell PowerEdge, a NAS server provides superior availability. The Dell server relies heavily on the NOS to provide stability and support. Because most NOSes are designed to support numerous applications, services and hardware platforms, it's not surprising that an occasional error should surface. When your server crashes and Dr. Watson comes knocking, someone had better be ready for some quick troubleshooting. NAS servers, on the other hand, undergo extensive regression and interoperability testing before they ever get to the customers' sites. The NAS servers' optimized OSes are often embedded in solid-state technology and therefore require little or no maintenance. If a patch or upgraded OS is needed, it can be applied easily through the administrator GUI in a matter of minutes. In our testing, higher loads produced some errors on a few of the NAS servers. However, these errors were generally insignificant and had little effect on throughput.

NAS servers, unlike conventional NOS-based file servers, are shipped already optimized not only for performance, scalability and stability, but for security. These NAS servers strip the NOS down to only the required critical system functions. By trimming that fat, the number of potential security exploits falls dramatically. There are no rogue services running in the background to be hacked. Additionally, because applications cannot be executed locally, there is little chance for the OS's integrity to be compromised.

However, NAS servers' authentication model still needs development. Although all the units we tested support both NIS (Network Information Services) and Windows NT domain authentication, only the Excel/Meridian and JES NAS servers, based on the Microtest FileZerver NAS engine, support NDS integration.

The servers also lack support for Kerberos. Given that NAS servers are particularly well-suited for a heterogeneous environment, we would have liked to have seen some form of native Active Directory or Kerberos support.

Stress-Testing NAS

The object of our tests was to create a high-stress environment that could challenge the servers' integrity. In our tests, we set up several read-and-write operations and increased the load in 10-user increments up to 200 users. We power cycled all the boxes repeatedly during normal operation to test the file systems' integrity, and in most cases, the NAS servers were back up and running in less than a minute without any adverse effects. Our Dell server survived the tests but required up to 10 minutes to get back online.

When we last looked at NAS servers, a little more than a year ago ("Lab-Tested: All That NAS"), there were only a few mainstream NAS servers available. The midrange market was especially underserved; choices were limited to small workgroup NAS servers or expensive high-end models. The market has matured dramatically, and dozens of storage vendors and integrators have jumped on the bandwagon.

The application of NAS servers varies, depending on the market in which the servers are deployed. Smaller workgroup NAS servers, such as Maxtor Corp.'s MaxAttach device or Quantum's Snap Server, are designed almost exclusively for end-user content distribution. On the other end, enterprise NAS servers from companies like Auspex Systems, EMC Corp. and Network Appliance are used almost exclusively in the vertical markets as back-end storage repositories for data warehousing, e-mail spooling and mailboxes, and Web server content.

A midrange NAS server, which we defined as providing 200 GB to 700 GB of storage and costing less than $50,000, fills a sweet spot in the market because it can service front-end client storage or back-end vertical markets. Ranging from $5,000 to $50,000 each, these midrange servers are relatively inexpensive and easy to deploy, yet capable of scaling to larger environments.

In our Real-World Labs® at the University of Wisconsin-Madison, we evaluated these midrange servers for their ease of setup, administration and supported features, as well as SMB (Server Message Block) file-serving performance under increased user loads. After the numbers were tallied, Network Storage Solutions' Thunderbolt R500 wins our Editor's Choice award, with superior performance and manageability. With a solid mix of features and performance at a great price, Excel/Meridian's Excel NAS Drive Z Server (an OEM version of Microtest's FileZerver engine) earns our Best Value award. Procom Technology's NetForce 1500 stumbled a bit in performance but offers a robust feature set at a good price. Conversely, the Land-5 Icebox had great performance in our tests but lacks the features found in the other NAS servers. The high-priced Network Appliance NetApp F720 fell short on performance but offers the best features and support. The JES Raptor RAID IDENASRAID636 (an OEM version of Microtest's newly released IDE NAS engine), performed slightly below Excel NAS and suffered from some teething difficulties that manifested themselves as stability problems.