Open source-based NAS appliances

Open source NAS devices on the hot seat: Snap Appliances edges out competing products from FAI and American Megatrends in tests conducted by Miercom.

Open source enthusiasts, particularly Linux advocates, make much of the inherent systemic and cost efficiencies of Unix operating systems. To ascertain how the beauties of an open source operating system are brought to bear in departmental network-attached storage  appliances, we invited makers of these products into our labs.

Consistent with the notion that you get what you pay for, these products are less than stellar as a group, particularly with regard to management. Also, the best product was also far and away the most expensive. But from among the three vendors that submitted their products, Snap Appliance's Snap Server 14000 performed well enough across our criteria to win the Network World Blue Ribbon Award. The two other systems tested were StorTrends 2104 from American Megatrends (AMI) and FIA's  POPnetserver 4600. We evaluated the NAS appliances in four categories: ease of installation, hardware configuration/features, management and performance.

Snap Appliance

You can argue that Snap's strong showing reflects its considerable experience as a NAS appliance vendor. But the model we tested, the Linux-based Snap Server 14000, is considerably more expensive than its two competitors. A standard Snap Server 14000, with 1G byte of RAM and 12 120G-byte drives, costs $16,000. An AMI StorTrends 2104 with 512M bytes of RAM and no drives is priced at $2,300; and FIA's POPnetserver 4672 with 512M bytes of RAM and four 180G-byte drives is priced at $3,500.

Installation was easy thanks to an effective install wizard. Snap's Quick Install guide was the best we've seen - this installation wizard was the only one that prompted for a change of the default password. Our only complaint was the need for frequent reboots throughout the process.

Redundancy features abound, including RAID 5 with hot spare; hot swappable drives; and redundant power, fans, and Ethernet interfaces with load balancing capabilities. It also offers two integrated software features: ETrust Antivirus software from Computer Associates, and its own Integrated Backup Express, software that lets up to five Snap servers back up to a single tape device. When testing features, however, the process of administering snapshots was unnecessarily difficult, and the documentation failed to address our questions.

Snap Server's management application, Administration Tool, was easy to use but had some shortcomings. Logs give you a lot of information, but they're difficult to understand and cannot be exported as data files. Also, no real-time statistics were available on Administration Tool, nor did it offer any diagnostic capability.

These last two complaints can be addressed by accessing Snap Server's command-line console via a Secure Shell-encrypted connection. This gives considerably more visibility into the box, including a large number of real-time statistics. It also is the only means of accessing simple IP diagnostic tools such as ping and trace route.

The strength of this product is its performance (see performance chart). With a maximum throughput of 1.83M byte/sec, performance in the file server client emulation testing was marginally better than the others. During Web server emulation testing, however, the Snap product distanced itself quite a bit, posting a maximum throughput of just less than 21M byte/sec. However, Snap's resilience to denial-of-service (DoS) attacks was unimpressive, incurring a 17% performance hit while under attack. (See chart.)

FIA

Installing FIA's POPnetserver 4600 was very nearly a plug-and-play exercise. Just a few clicks through FIA's setup wizard, and you have instant storage.

But there are a couple of caveats that prospective FIA buyers should beware of. Our testers complained the automated setup process bypassed any initial user setup, and "Guest" accounts were left with read and write access to the default directory - a considerable security oversight.

Secondly, FIA customers who lose or forget the administrative password must ship their POPnetserver back to the dealer for installation, and, astonishingly, all data on the server will be lost.

FIA runs its NAS product on FreeBSD. The POPnetserver 4600 supports RAID 5 plus hot spare, a RAID configuration that reserves an additional hard drive to swap in immediately when a drive fails. Other redundancies include hot-swappable drives and load-sharing Ethernet interface cards. However, volumes cannot be expanded on FIA's device without resetting it.

FIA boxes can provide full-featured back-up functionality, but at a price. FIA offers POPbackup, Data Replicator, Snapshot Backup and Server-to-Server Replicator as optional, extra-priced software. Our testers found that each of these products worked as advertised and were easy to use. Missing from FIA's repertoire, however, is antivirus software.

Through the POPmanage browser-based application, management of the POPnetserver 4600's is fairly straightforward. We cited the logs for offering a lot of data clearly.

The holes in FIA's overall management capabilities are statistics that offer only a handful of items that can be monitored, and there are no IP troubleshooting or diagnostic capabilities. Logs can be exported, there are no other reports to be had, and FIA's is the only device under review that does not protect its management access to the NAS via Secure Sockets Layer-encrypted communications. Perhaps most egregiously, FIA has no console port through which you can access the box when all else fails.

The performance of the FIA NAS appliance also was wanting, registering 1.52M byte/sec maximum throughput in the file server scenario; and just more than 11M byte/sec in the Web client emulation, the lowest metrics of all systems tested. However, FIA scored higher in performance than it otherwise would as the result of its exceptional resilience to DoS attacks, with performance degrading only 4% while under a DoS attack.

American Megatrends

AMI's StorTrends 2104, which runs on Linux, is particularly geared toward price-conscious buyers. While AMI achieved this goal, it did so at the expense of some important attributes, such as effective management, redundancy features and performance.

Installing the StorTrends 2104 is difficult. There's no installation utility, and the Quick Start documentation was not particularly useful. The set-up console was menu-driven, but there was no guidance offered, including Help. To make matters more difficult, some software bugs impaired our engineers' ability to deploy the box incident-free.

The configuration of the 1U appliance gives buyers some value for the dollar. Despite its low price, the StorTrends 2104 supports the most powerful processor of the Unix systems tested (Pentium 4/2.4 GHz), and the most system memory (up to 3G bytes). However, it is missing some important redundancy features, such as hot-swappable drives and redundant Ethernet interfaces. While it likely was done to keep down the cost, storage devices as a rule should give a little more consideration to disaster-proofing.

StorTrends 2104 offers a single power supply, a single fan and no network connection fail-over functionality. Moreover, there is no redundant or hot-swappable drive capability, and administrators are forced to reset the box after expanding a volume or adding a disk drive.

AMI's browser-based management interface, SRM Express Management, is a clean, well-organized application that promises to be an effective tool. But like many aspects of the StorTrends 2104, it's not quite there yet. SRM Express includes a network topology map, real-time utilization graphs and some robust reporting functionality.

However, there were two serious flaws. AMI's logs cannot be sorted or filtered, and they're difficult to understand. Second, AMI's Snapshot implementation doesn't allow automatic scheduling. Snapshot software, an important value-add for NAS products, makes instantaneous, point-in-time copies of the system's file directory at configured intervals that can be used to retrieve corrupted or wrongfully deleted files.

Still more bad news concerning AMI's showing is that it does not support antivirus software, nor does it offer or support any software for performing full backups of its drive contents. Finally, AMI's performance test results did little to distinguish the product.