Low-Cost NAS

Most NAS systems with enterprise-class storage and security still hover around the $5k mark, but we found -- and tested -- five solutions with at least 1 terabyte of storage

April 6, 2006

24 Min Read
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For more than a decade, network-attached storage systems have housed enterprise applications, acting as primary storage for departmental and remote offices and as dedicated storage pools for disk-to-disk backups. Small businesses also have discovered the benefits of storage consolidation, not only to provide a safe and controllable repository for business data, but to support shared data for network users.

Because of its reasonably low cost and ease of use, NAS is ideal for these storage needs and more. It runs on Ethernet, works seamlessly with every computing platform, and doesn't require years of storage management experience to run. The smallest segment of the NAS market, systems that cost less than $500, has exploded over the past two years, and more than 500,000 such microstorage systems--nearly 90,000 TB of data storage--will be sold in 2006, according to Gartner Dataquest. Although amazingly inexpensive, these commodity NAS appliances are usually single-drive systems that don't offer enough data protection for many business storage needs.

For this review, we considered the next tier of affordable NAS: Systems that offer enough capacity, security and storage management to make them a good fit in practically any business environment. We put out a request to vendors for entry-level NAS systems that cost less than $5,000, supply at least 1 TB of raw storage, offer parity-protected RAID 5, and provide native support for both CIFS and NFS file systems. Of the 10 companies we contacted, only five heeded the call: Aberdeen, Adaptec, Hewlett-Packard, Infrant Technologies and Prime Array Systems. Four of the other invitees, Buffalo Technology, Iomega, LaCie and Network Appliance, did not have systems that fit our criteria. And though Dell showed initial interest in our review, the company never responded after receiving our invitation and multiple follow-ups.

The five systems we tested vividly illustrate the NAS platform's variety and flexibility. System design, for example, runs the gamut from Infrant's toaster-sized NAS appliance to HP's midtower standalone Storage Server, with 1U and 4U rackmount models in between. Two systems, Aberdeen's AberNAS 128, and HP's ProLiant ML310 G3 Storage Server, are based on WSS (Windows Storage Server 2003). The other three, PrimeArray's FlexNAS 6800E XT, Adaptec's Snap Server 520 and Infrant's ReadyNAS NV, use an open-source kernel optimized for storage. Prices range from $1,299 to $4,995, and these systems generate a matrix of impressive storage-management features that clearly reflect the NAS platform's growing maturity, even at entry level.

Christmas in January

There's nothing like the smell of new storage in the morning, so we crossed the frozen tundra of Green Bay, Wis., to get to our Real-World Labs® and set up our stack of nifty new NAS devices. We began by building a test network to emulate the workload we would expect from a midsize workgroup: three Dell servers, a Nortel Gigabit Ethernet switch, and a separate workstation for managing the Iometer performance tests. Our test scenario simulated 12 systems hitting the NAS at the same time. That's a heavier load than you'd expect in a typical office, where network data access is much more sporadic, but it was large enough to see some differences in how the systems handled the stress. With systems at this price, we were expecting to see read performances near 100 MBps, or close to the maximum bandwidth of a single Gigabit port, and write performance that would run 25 percent to 30 percent below that.

The process of setting up the file system on each test NAS system varied little, and each system came preconfigured with all four hard drives set up as a parity-protected RAID 5 array. The rest of the process involved logging in to the Web management interface, setting up a static IP address, creating folders on the system's root directory, enabling CIFS and/or NFS protocols and setting up user access permissions. Each system supported domain and user authentication, as well as open shares, and all let an administrator set usage quotas and generate e-mail or SNMP traps to monitor system status. Although the Windows machines from HP and Aberdeen were almost identical for setup, all five test units used surprisingly similar management interfaces--with help screens and setup wizards for inexperienced users.The Number of NICs

With a separate shared directory mapped as a network drive on each of our three test servers, we dove into our Iometer performance tests. One of our challenges was to fairly compare the three systems that offer dual-Gigabit Ethernet NICs with the two that offer only a single port for storage. As a rule, we try to test all systems under identical circumstances, so we first tested both single- and dual-port systems in single-port mode, and systems with dual NICs were set to failover. In larger environments, when networked storage devices have dual NICs, they are often set to failover, so if one link to the storage is lost, another can take its place. The alternative to this is link aggregation or load balancing, which lets you combine two NICs for higher throughput. This feature is well-suited to smaller environments that don't necessarily require using the NICs in a redundant, failover mode and would instead opt for the higher performance of a load-balanced system.

Next we used the load-balancing feature, rather than link aggregation, because of its compatibility with most environments. Link aggregation requires switch-level support, and the increase in available bandwidth would be about the same in either of the dual-NIC modes. We also tested the fault-tolerance of the load-balancing setup by unplugging one of the links during testing. In all three cases, the performance immediately dipped to single-port speeds but, as expected, the connection to our servers was never completely interrupted.

We also tried reconnecting them during the test, but only the Snap Server and FlexNAS could reacquire the link and come back up to full speed; the AberNAS required a system restart to resynchronize the load-balanced connection. These results also confirmed that there is no good reason to limit the performance of dual-NIC systems by using them in failover mode, because load balancing offers reasonable fault tolerance for single-network environments.

With load balancing enabled, we were pleased to find that the performance of AberNAS 128 and the Snap Server 520 just about doubled: combined reads reached nearly 200 MBps and writes pushed 150 MBps. The Snap Server and FlexNAS systems made this process the easiest, letting us toggle between modes, but the WSS-based AberNAS forced us to drop to the OS to set up the NICs. PrimeArray's FlexNAS 6800E XT didn't really push the upper limits in our single-port tests in the first test, so enabling load balancing actually decreased its performance a tiny bit. Of the other two systems, only HP's ProLiant ML310 G3 came close to matching the single-port capabilities of the systems from Aberdeen and Adaptec. The low-priced Infrant ReadyNAS NV came in last.Application vs. Performance

With entry-level storage systems, application is everything and performance is only part of the picture. To evaluate our NAS systems, we used five criteria: features, performance, price, scalability and management. The real challenge lies in finding the best combination of factors for your organization.

With this in mind we chose to use equal weighting for all our criteria and, when we tallied all the scores, Adaptec's Snap Server 520 earned our Editor's Choice award. The 520 is the middle system in Adaptec's new 500 series of 1-U NAS systems, which includes the slightly smaller 510 and the larger capacity, higher performance 550. Middle of the line or not, the Snap Server 520 performed impressively, and won three of four read/write tests with load-balanced, dual NIC numbers rivaling those of 2Gbps Fibre Channel. This performance, combined with the flexibility, security and excellent suite of features of the Snap Guardian OS, made the Snap Server 520 a natural choice.

We had a dead heat for second place, between HP's ProLiant ML310 G3 and Aberdeen's AberNAS 128. Priced almost identically when you factor in the extra terabyte of included disk storage, the AberNAS 128's excellent performance statistics ran neck-and-neck with the ML310 G3's flexibility and impressive remote management capabilities. Both systems offer the familiarity of the WSS user interface, and have all the right stuff for many small business and departmental applications.

We were only a little surprised to find that the least expensive and most expensive systems came in equally rated. The ReadyNAS NV's combination of low price and useful features was offset by its low performance ratings, while the FlexNAS 6800E XT's high cost and midline performance overshadowed the unit's nice features and scalability. Although performance can be an issue in larger environments, each would be suitable for less storage-intensive business applications.Adaptec Snap Server 520

Snap Appliance has changed ownership twice in the past few years, and it's no secret that Adaptec has been looking for a new buyer for its Snap and Eurologic divisions since late 2005. In spite of these distractions, the Snap Server engineers have hit the nail on the head with this generation of NAS systems, equipping them with server-class, 64-bit Opteron processors and supporting economical SATA drives or SAS (Serial Attached SCSI), the next generation of high-performance SCSI drives.

The Snap Server 520 we tested came with a single-core 2.2-GHz AMD Opteron 248 processor, 512 MB of RAM and four hot-swappable SATA 250-GB hard drives. As a bonus, Adaptec incorporated an SAS drive backplane interface in its design, so you can upgrade to 500-GB SATA drives or a higher-performance SAS controller/drive combination. The system also offered dual Gigabit Ethernet ports, an integrated Ultra-320 SCSI controller for direct connection to tape systems, one half-height and one full-height PCI-X expansion slot, and a single power supply. There was even room for a second, optional power supply for load balancing and failover.

The system runs on Guardian OS 4.1, which supports the software RAID and the abundant integrated features that edged Adaptec above the rest. The Web management interface is easy to use, with context-sensitive help available for every function. A multiplatform, client-side management application is available. The Snap Server 520 includes CA's eTrust virus protection, backup services by BakBone NetVault, quota management, automated volume snapshots and full support for virtual iSCSI disks at no extra charge.This iSCSI capability is available at additional cost from several of our other vendors, but iSCSI support has been standard on the Guardian OS for a long time. The Snap Server 520 lets you easily create and manage SAN-like, iSCSI LUNs (Logical Unit Numbers) to satisfy applications that demand block-level storage. The iSCSI LUNs can be accessed by any system with a conventional NIC using Microsoft's free iSCSI Initiator software. Multiple LUNs can be added to any volume on the 520's file system.

Supporting these features requires storage virtualization. To handle this task, Adaptec offers a feature called Instant Capacity Expansion. ICE is a powerful provisioning tool at the core of the Guardian OS that lets you add new disks to storage arrays and expand volumes without moving data or tearing apart existing arrays. This greatly simplifies the addition of disks for both file and block purposes. The 1U Snap Server 520's storage capacity can be expanded to 25 TB by adding up to four 12-drive SANBlock S50 JBOD disk enclosures. This SAS/SATA, 2U rack enclosure incorporates an external SAS interconnect that supports transfer rates of up to 2,400 MBps in full-duplex mode.With its impressive mix of performance and features, the Snap Server 520 also nears the top of our price range, at $4,595. The system's flexibility makes it a great choice for many business apps, especially in environments that need both file and block-level storage. The Snap Server 520 has a limited three-year warranty on hardware and 90-day software coverage, and Adaptec offers numerous extended support options.


Hewlett-Packard ProLiant ML310 G3 Storage Server Hewlett-Packard takes a server-based approach to its NAS systems, and the ProLiant ML310 G3 is also sold as a general-purpose server. The main difference between the NAS, priced at $3,468, and the server version is the combination of software and drives installed. In our tests, the ML310's dual-core processor led the way in sheer computing power, with massive IO-per-second performance that proved it had muscle to spare. Although the server offers reasonable single-NIC performance, the availability of only one Gigabit Ethernet port limited its read/write performance, especially when compared with the dual-NIC, load-balancing systems from Adaptec and Aberdeen.

The ProLiant ML310 G3 Storage Server we received was a standalone, midsize vertical tower with a dual-core Intel Pentium D 830 3-GHz processor, DVD R/W drive and four 250-GB SATA hard disks. Our test system came configured with only 512 MB of RAM and we learned--after testing was completed--that HP normally configures the 1-TB version with 1 GB of memory. HP's hot-swappable drive enclosure, like Adaptec's, uses an SAS backplane, even though HP doesn't offer an SAS option for this system. The tower case has two 5.25-inch external drive bays for additional optical or tape drives, and the system board has two available PCI-X and one PCI-E slot for add-on cards.

The 1-TB system comes with a six-port SATA hardware RAID controller and dual Gigabit Ethernet NICs; however, one of the network ports is dedicated for use by the unit's ILO (Integrated Lights-Out) 2 feature. This "computer within a computer" lets you remotely monitor and manage key system functions, such as power, event logs and system status, using a browser, regardless of the OS's status. ILO 2 is a major plus for remote offices.

The NAS OS is WSS 2003, Workgroup Edition, making the ProLiant ML 310 a natural for integration into Windows environments. Snapshots are handled by the VSS (Volume Shadow Services) features built into Windows. Shared folders from multiple NAS systems can be published in a shared namespace by using Microsoft's DFS (Distributed File System) storage virtualization technology. Although the ProLiant can run any Windows software, HP supports only user-added applications that relate to its primary task as a storage server. The system's storage capacity can be expanded by up to 16.8 TB through the addition of an HP Smart Array 642 Controller card and external, Ultra-320SCSI, 14-drive MSA30 disk arrays.The warranty covers one year for parts exchange, one year labor, and one year on-site with next business day response. HP has many extended-support options available.


Aberdeen AberNAS 128 Aberdeen's AberNAS 128 was the only 2-TB system we tested. This NAS has the largest native capacity and the horsepower to go toe-to-toe with the Snap Server in both our load-balanced and single-port performance tests.

The 1U, rack mount AberNAS 128 was equipped with a single 3-GHz Pentium 4 processor, 512 MB of RAM and four hot-swappable 500-GB SATA II data drives, plus a dedicated internal drive to hold the Windows Storage Server OS, and priced out at $4,495. The system also offered a DVD-ROM drive, one power supply, and two Gigabit Ethernet ports that supported failover, link aggregation and load balancing.

Because the AberNAS 128 is also based on WSS 2003, it offers practically identical basic software features as the HP ML 310. From a storage standpoint, however, Aberdeen surpasses HP. For starters, the AberNAS 128 uses an advanced SATA II hardware RAID controller combined with 3-Gbps SATA II hard drives. In this case, the increase in SATA bus speed alone probably doesn't affect the array's performance as much as its ability to take advantage of SATA II's Native Command Queuing does. This might explain its markedly higher scores in our difficult NWC Custom Test. Performance was further improved by the availability of dual, load-balancing NICs.

The AberNAS 128 posted both single-port and load-balanced read/write performance that fell within a few percentage points of Adaptec's winning scores, and won the NWC Custom Test outright. Overall, the AberNAS's combination of performance and features let the device tie HP's score on our report card, though Aberdeen doesn't offer the same depth of software support and expansion capabilities as HP or Adaptec. The AberNAS systems aren't designed to be expandable through add-on external drive enclosures; but because of Microsoft's DFS capabilities, multiple AberNAS systems can be virtualized into a clustered single namespace.

Despite coming from a smaller vendor, the AberNAS 128 boasts outstanding features. This well-designed system would be a great choice for many small business and workgroup applications and, to back it up, Aberdeen offers an impressive, five-year parts and labor warranty; though the system must be returned to the factory for service. Extended on-site service contracts are available, and free 9-to-5 telephone support is provided for the full five years. Aberdeen also has a standing offer of a free, 10-day trial period on any of its storage or server systems.

www.aberdeeninc.comPrimeArray Systems FlexNAS 6800E XT The most expensive system we tested, priced at $4,975, the FlexNAS 6800E XT offers a number of high-end features, such as dual power supplies and multiple NICs, but its performance was below par. PrimeArray offers other NAS systems with faster processors and SATA disks that would likely offer better performance than this model, but those may not have offered the same features or matched our price requirements.

The FlexNAS we tested came with a 1.26-GHz Pentium III processor, 512 MB of RAM, and four 250-GB PATA drives mounted in hot-swappable drive trays. The 4U rackable chassis offers dual Gigabit Ethernet NICs, redundant power supplies and room for two 5.25-inch optical or tape drives as well as four extra drive trays for additional PATA hard disks. The hardware RAID controller supports RAID 0, 1 and 5 with hot spares, and dynamic, on-the-fly RAID expansion up to the system's 2-TB maximum volume.

Initial network configuration can be done with the front-panel LCD interface, and the custom NAS OS can be accessed from a Web browser or a Windows management client. The base system offers all the necessary features to control file management, security and virus protection, but many of the high-level features, such as snapshots, certain backup-related items and tape library support, require additional licensing.

For such an expensive system, its performance was disappointing. Only the Infrant ReadyNAS, which sells at almost one-fourth the price, did worse. It's likely that the system's below-average performance is the result of the use of older PATA drive technology, in combination with the older and slower Pentium III processor. Furthermore, though the dual NIC configuration supports load balancing, enabling it resulted in a decrease in performance.

On the plus side, the FlexNAS offers a number of unique, CD/DVD-based features, such as disk imaging, caching and sharing, and tools for disk writing and data archiving. These require additional licensing. The FlexNAS system also offers SmartSync block-level data replication, and the optional SmartExtend feature lets you cluster up to 10 FlexNAS systems--up to 26 TB of capacity on one logical server. Although this system would have performance problems in larger environments, its expansion capabilities and CD/DVD options are well-suited for smaller environments with mixed-media requirements. PrimeArray offers a one-year warranty, with an optional two-year or three-year extended warranty. Phone and e-mail technical support are available from 9 a.m. to 6 p.m. ET, Monday through Friday. PrimeArray provides no on-site support services.


Infrant Technologies ReadyNAS NV Inexpensive NAS options have proliferated in the past two years, but the ReadyNAS NV is one of the few low-cost systems that met our criteria. At nearly one-third the price of its closest neighbor, the unit surprised us with a substantial set of storage features, and though its performance was the lowest of our test systems, it really wasn't that far out of line--especially when you take into account its diminutive, $1,299 price tag.

The ReadyNAS NV measures only 8 inches by 5 inches by 9 inches, and is based a single RAIDiator 2 storage processor that manages all system functions, including hardware RAID, Ethernet and USB I/O. The RAIDiator NAS firmware resides on an internal 64-MB flash card, and the system has 256 MB of RAM, a single Gigabit Ethernet port and four hot-swappable 250-GB SATA hard disks that sit neatly behind its front door. The disk system offers RAID 0, 1 and 5 with hot spares, along with Infrant's proprietary X-Raid technology, which supports automatic volume expansion if you choose to migrate to larger drives later.The first surprise from Infrant was a nifty management application called RAIDar, which scans your network for any available ReadyNAS systems and presents them in a window--complete with address information and status indicator lights. From there you can log directly into the Web management interface, where we found features rivaling many of those in our other NAS systems. The system offers all the same protocols, security management, snapshot and system-monitoring capabilities, but Infrant adds some useful services, such as multimedia streaming, one-touch backups and automatic USB data transfers from Flash media.

The downside is in performance, where single-port read statistics were about half those of most systems, and writes hovered at about 16 MBps, or one third that of the other systems. In the IOps test, which stresses the processor, performance dropped to about 10 percent of the competition's--more than likely because of its single-chip design. To be fair, this system is not marketed or priced as a workgroup solution, so it's doubtful the ReadyNAS would find itself hammered by 12 systems simultaneously. However, our test results are designed to provide an honest representation of its performance relative to the other systems in our group, and to Infrant's credit, this was a 33 percent increase in performance over the earlier ReadyNAS X6 system.Although it's unlikely the ReadyNAS would make the shortlist for critical apps, the ReadyNAS NV's combination of low price, data security and advanced storage features make it an excellent choice for a large number of noncritical business and SOHO apps. It comes with a one-year limited warranty, and support options are limited to e-mail, online FAQ and live chat during business hours. No extended support plans are available.

Steven Hill is a Network Computing technology editor. He has previously held positions as a department manager and imaging systems administrator for a Fortune 500 corporation based in the Midwest, and has more than 30 years' experience working with photographic and digital imaging technologies. Write to him at [email protected].


How We Tested

To test sub-$5,000 NAS systems, we created a dedicated storage network designed to emulate the stress created by 12 users concurrently accessing them at 100 percent. To do this we used three Dell servers: one PowerEdge 2650, with dual 2.4-GHz Xeon processors and 2 GB of RAM; and two new PowerEdge SC 1425's, with dual 3-GHz Xeons and 3 GB of RAM. Systems were networked using a Nortel 5510-48 Gigabit Ethernet Datacenter Switch, and connected to each Dell using the dual, internal Gigabit Ethernet NICs, set to failover mode. Each NAS was configured with one active Gigabit Ethernet port set to a static IP address, and those with multiple ports were assigned to fail-over. Jumbo frames and port bonding were not enabled to minimize network-related inconsistencies.Each NAS system was configured as a four-drive, RAID 5 array, and each server was assigned a dedicated CIFS folder that was mapped as a network volume. We used Iometer .2004.07.30 to create a 300-MB test file which was copied to each of the three folders on our NAS systems. Each server ran a single manager with four workers, and tests were run using 12 workers. All tests were configured to allow one outstanding I/O and set to run for two minutes with a 20-second ramp time.

We used linear read/write tests to measure combined raw data throughput for both small (64 KB) and large (1 MB) file transfers. We set the read/write distribution to 100 percent for both the read and write tests. Random/sequential distribution was set at 100 percent sequential and measurements are tabulated in total MB per second.

Our IOps (I/O operations per second) read test is designed to test storage processor performance on very small transfers, and uses a 512-byte transfer request set to 100 percent read, 100 percent sequential. Performance is measured in total IOps.

The NWC Custom Test is a mixed set of concurrent reads and writes designed to stress the entire system with a simulated workload. This series is set to transfer request sizes of 8 KB with 33 percent access distribution, 8 KB with 34 percent access distribution, and 64 KB with 33 percent access distribution. On the first 8-KB segment, we set the read/write distribution to 100 percent read at 100 percent sequential. On the second 8-KB segment, we set read/write distribution to 67 percent read and 33 percent write at 100 percent random. On the 64-KB segment, read/write distribution was set to 100 percent read at 100 percent sequential, and results are measured in total MBps.

All Network Computing product reviews are conducted by current or former IT professionals in our own Real-World Labs®, according to our own test criteria. Vendor involvement is limited to assistance in configuration and troubleshooting. Network Computing schedules reviews based solely on our editorial judgment of reader needs, and we conduct tests and publish results without vendor influence.Executive Summary

How much network-attached storage will $5,000 buy? If you're a small business looking for secure, manageable storage, the answer is plenty. We put out a call for affordable NAS systems with at least 1 TB of storage, with security and storage management. Five companies rose to the challenge: Aberdeen, Adaptec, Hewlett-Packard, Infrant Technologies and Prime Array Systems. Adaptec's entry impressed, and earned our Editor's Choice award. The $4,595 Snap Server 520 has a wide range of integrated features and performed brilliantly in our tests. It was also one of only two systems that passed our "unplugged" fault-tolerance test, by re-establishing a link and returning to full speed immediately after reconnection.

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