Midrange Windows-powered NAS devices

Testing Windows-powered NAS devices: Network World Global Test Alliance partner Miercom tested products from HP and Inline.

Microsoft‘s release of its Windows 2002 Server Appliance Kit two years ago let traditional server vendors such as Dell, HP and IBM enter the network-attached storage appliance market, which had been dominated by Auspex, EMC and Network Appliance. Today, Windows-powered NAS devices have about a 25% share of this market, according to IDC.

We invited all vendors with Windows SAK-based products to participate in a comparative review – including Dell, IBM and Iomega  – only HP and Inline were game to play. The Network World Blue Ribbon Award goes to HP’s StorageWorks NAS b2000 primarily on the strength of its performance. Inline, with its FileStorm 4550, sported some innovative features but came up short when otherwise compared. We evaluated the appliances in four categories: ease of installation and management, hardware configuration, features, and performance.

Setup

StorageWorks NAS b2000 uses a ProLiant DL380 server platform, which builds on HP’s experience as a server manufacturer. Take, for example, HP’s RapidLaunch utility. It provided prompt-driven installation that resulted in quick deployment and management access to the box.

RapidLaunch requires no Dynamic Host Configuration Protocol server access to set up the NAS. It discovered all network-attached elements and assigned an appropriate IP address to the NAS. Our only complaint was that the default administrative username and password were nowhere to be found on “Quick Start Guide” documentation, an annoyance that HP promised to fix in its next release note.

Conversely, installing the Inline device was a journey of discovery. There was no utility offered for initial installation, and the “Quick Install Guide” was insufficient for the task. We were eventually successful, only with heavy reliance on the main user manual.

NAS-SAN integration

Two configuration characteristics that separated these two systems both favored Inline. An Inline FileStorm 4550 can contain up to 8G bytes of system memory, as opposed to HP’s 6G bytes. Also, Inline supports up to a maximum of four processors, while HP supports only two.

But perhaps the most important difference between the two products lies in their architectures. HP’s device is an off-the-shelf ProLiant DL380 server running Windows SAK. It is a self-contained storage unit with SCSI connectivity for expansion cabinets that can accommodate up to 27 terabytes.

The FileStorm 4550, however, is essentially a head-end device with no internal storage resources, except for what is required for storing the operating system. The device contains the intelligence to provide connectivity and file services to users, but storage resources are external only. This could be in the form of a SCSI-based expansion cabinet or a Fibre Channel storage-area network (SAN).

Serving as a NAS head for a SAN, the FileStorm 4550 can present the storage resources of a back-end SAN as if they were local on the NAS appliance. As tested, the Inline system is a two-chassis solution. Along with the FileStorm 4550 NAS head, storage was situated on an Inline TruFibre expansion cabinet, which was accessed via a Fibre Channel link.

Another hardware aspect of the Inline box is the operating system on the FileStorm 4550 that was stored on solid-state disks (SSD), which are available on the Inline product as an optional item. With SSDs, data is stored on erasable programmable read-only memory rather than on conventional, magnetic disks. With no moving parts, SSDs are significantly faster than conventional disks, but they’re also significantly more expensive.

Even without SSDs, an Inline 4550 is not inexpensive. Configured with two Xeon MP processors, 4G bytes of RAM, two Fibre Channel host bus adapters, and no internal drives, it costs $28,200. An HP StorageWorks NAS b2000 with one processor, 1G byte of RAM, two, 36G-byte drives for internal storage use, and three 146G-byte drives for client storage use is priced at $8,000.

Hardware redundancy is solid for both products with both featuring hot-swappable disks, N+1 power supplies and multiple redundant fans. Inline offers four, load balancing Gigabit Ethernet NICs while HP offers dual, load-balancing Ethernet NICs. HP also features hot spare memory and memory mirroring. Inline adds cache mirroring on redundant disk controllers.

Features

Inline made a strong showing in the features category. TruMask is software that enables logical unit numbers (LUN) masking on an Inline storage cabinet. LUNs are essentially resource target addresses. LUN masking is a security feature that makes user-defined target resources invisible to specific Fibre Channel-connected computers.

TruMap is a virtual-LAN-like feature that maps storage resources to specific physical ports. Access to those resources, then, would be available only to requests entering through that port.

Finally, TruCache lets redundant disk controllers mirror one another, providing instantaneous failover in the event of disk controller failure.

HP’s most notable software feature is StorageWorks’ NAS Data Copy software, which lets data be replicated over an IP network to a redundant StorageWorks box. If a link or system fails, users request failover to the redundant NAS, and fail back when the primary is restored.

HP’s Integrated Lights Out (ILO) is a feature of the underlying ProLiant DL380 server platform. Embedding the ILO software on a dedicated processor, complete with its own Web server, allows browser-based terminal emulation of the StorageWorks console in the event of connectivity loss or system malfunction.

Windows management

To manage a Windows SAK-based NAS is to manage a Windows 2000 Server. There are server management utilities that Windows does well, such as Performance Monitor and Event Viewer. The problem is that to access these handy management utilities or manage the appliance’s hardware, administrators must have physical access to the NAS or launch a Terminal Services session with the server. Windows SAK platforms prohibit the ability to develop their own management applications that integrate all NAS management functions – and even multiple NAS devices – into a single interface.

Browsering into both products gave us the same interface. But HP’s well-known server utilities made managing their offering a better experience. One example was called Survey Utility. This provided a lengthy, well-organized log of all administrative changes – hardware and software – performed on the NAS.

Also, Windows SAK-based systems leave the onus of RAID array management to the vendors. HP’s Array Configuration Utility made RAID-related tasks – such as creating and defining an array or adding disks – a simple exercise. By contrast, Inline’s MorStorView was not intuitive and required much getting used to.

Performance

Each vendor provided a product populated with four internal drives and as much memory and processing power as needed for optimal performance. HP tested with two Intel Xeon 2.8-GHz processors and 1G byte of RAM. Inline submitted product with four Intel Xeon MP 2.0-GHz processors and 4G byte of RAM.

To ensure that each product’s disk subsystem was stressed equally, our test engineers baselined each product’s I/O cache capacity and then adjusted the traffic loads to send 30% more load than the system’s cache could handle (see How we did it).

HP’s StorageWorks outperformed the Inline FileStorm product in all performance categories, registering an average of 7.67M byte/sec throughput when we ran our file server client emulations against it and an impressive average of 76.38M byte/sec with Web server requests. Inline posted 6.26M byte/sec and 61.35M byte/sec, respectively (see Performance chart).

Additionally, HP’s resilience to off-the-shelf denial-of-service (DoS) attacks was impressive. The product proved impervious to our attacks despite multiple attempts. Conversely, Inline’s performance degraded by 26% during a DoS attack. (See chart.)

The interfaces attacked in HP and Inline’s cases were Alacritech network interface cards, but this has no bearing on the results of the DoS attacks, according to Alacritech engineers. The reason our DoS attacks affected Inline was because it performed RAID control in software, while HP’s RAID control is hardware-based.

HP StorageWorks NAS b2000 and Inline FileStorm 4550 approach the delivery of NAS functionality to enterprise customers differently. Inline’s less conventional approach, however, did not translate into performance advantages over HP’s plain old NAS server.