NAS devices comprise basic server hardware and storage components. Essentially, they're servers with a ton of storage. The secret sauce that turns these devices into turnkey appliances is specialized NAS operating systems. Some machines run the Microsoft SAK (Server Appliance Kit), a stripped-down version of Windows 2000 Server for use on NAS devices. With SAK, the NAS device can natively run some Windows software, such as backup agents. SAK also saves you the cost of a full-blown Windows server license for your NAS box. Many other NAS machines run a Unix variant, such as Linux or FreeBSD. Other companies have hand-coded their own tight kernels, which may seem impressive but often offer few advantages.

NAS Device Performance click to enlarge

NAS Lineup

To test midrange NAS devices, we invited 20 vendors to send us systems priced from $5,000 to $30,000. We asked for at least one copper Gigabit Ethernet port and recommended that vendors send 1 TB of storage with enough spindles to ensure maximum performance.

We received machines from Dell, Excel Meridian Data, First Intelligent Array (FIA), Hewlett-Packard Co. and Procom Technology. Advanced Media Services, Auspex Systems, BlueArc Corp., Delta Networks, EMC Corp., Gateway, Hitachi, IBM, JES Hardware Solutions, Network Appliance, Network Storage Solutions, RaidZone, Rare Systems, Snap Appliance and Sun Microsystems received invitations but declined to take part in our tests.

The participants all complied with the 1-TB minimum and included two or more copper Ethernet NICs. Prices ranged from $14,745 (for Excel Meridian's NetStor MVD) to $29,995 (Procom's NetForce 1800). Beyond the basics, however, we got quite a mix of hardware and physical configurations: internal disks, external disks, SCSI connect, Fibre Channel connect, and a multitude of Ethernet connections of varying speed and type.

Our tests gauged the performance of CIFS and NFS, using SourceForge's Iometer (see performance test results in chart on this page). In choosing our winner, we also considered ease of setup and administration, as well as fault-tolerance and scalability features, warranty and price.

To select the best NAS system for your enterprise, consider current and future storage demands, expected traffic and backup requirements. Your NAS should be expandable to suit your needs two years from now. Anticipating the traffic your NAS device will handle down the road will help you decide whether to get a second NIC on your unit and whether to use Gigabit Ethernet connections. And because you have several backup options, also think about your preferred backup method before you choose a device. Many NAS devices take a snapshot--a point-in-time backup of the current drive. However, snapshots take up space, especially if you use them extensively. You can make full backups with protocols such as NDMP (Network Data Management Protocol) or via a local tape, but your backup window and medium must be able to handle the additional stress the new NAS device may introduce.

On the hardware side, consider the importance of the data you are putting on the NAS. How fast does it need to be accessed, and how quickly does it need to be restored in the event of a failure? The faster you need that data, the more important multiple power supplies and redundant fans become. The drive choice is paramount: Conventional parallel ATA/IDE drives are slower and generally have less MTBF (mean time between failure) than their SCSI and Fibre Channel counterparts.

The combination of strong performance, a good warranty, flexible configuration and a decent interface make the Dell PowerVault 775N our Editor's Choice.