Network-attached storage (NAS) can provide scalability, manageability, and file-sharing benefits to a diverse user base.
By Zachary Shess
Throughout 1999, storage administrators were repeatedly invited to follow vendors' storage area network (SAN) roadmaps, offering avenues to heterogeneous file access and enhanced storage management. While these thoroughfares to storage interoperability remain under construction, network-attached storage (NAS) has emerged as a viable choice for administrators in need of easy-to-implement, scalable, heterogeneous file sharing.
NAS was slow to gain acceptance during the mid-1990s, in part because IT administrators were often uncomfortable with a new breed of server sold by relatively unknown vendors touting streamlined operating systems and heterogeneous file sharing.
As a result, NAS found a niche in CAD/CAM, video, and other data-intensive applications, which generate huge amounts of data and required large block transfers-tasks that stretch the limits of general-purpose servers.
Today, these issues are exacerbated by the vast amounts of Web-based data that is being created and stored. Whether it's an accounting office, a branch of the military, a university, an advertising agency, or an e-commerce firm, few organizations have enough IT resources to adequately handle the growing storage management duties.
Market statistics indicate that NAS devices are helping to solve these problems. According to International Data Corp., a market research firm in Framingham, MA, the NAS market was about $1 billion last year. In three years, it's expected to eclipse $5 billion.
To understand the potential benefits of NAS vs. host-attached storage, it's helpful to look at some user case studies.
University of Georgia
The Information Technology Outreach Services (ITOS) arm of the University of Georgia, in Athens, assists a variety of state and local agencies in creating, monitoring, and storing information for a wide range of activities.
To help gauge the effectiveness of the state's education system, for example, ITOS maintains a 35GB database that tracks the educational progress of every Georgia student from kindergarten through the workforce. ITOS also helps create and store hurricane-tracking computer models, and produces and maintains a repository for bandwidth-hogging geographic information systems (GIS).
To serve about 100 users working on 60 workstations, ITOS uses about 10 Unix and Windows NT servers, including Sun 450s and 2300s and Dell 2300s, 4200s, and 4300s. The servers are connected to a 12-port 3Com gigabit switch, which also links to a Dell PowerVault 740N, a NAS server based on technology OEM'd from Network Appliance.
Many ITOS employees using older Unix workstations running software RAID experienced up to 35-second screen refreshes when working on the GIS maps. Offloading that data onto Dell's 740N NAS server, and away from the rest of ITOS' server traffic, caused refresh times to drop to 5 seconds.
Since it can communicate to workstations and other servers via the NFS and CIFS protocols, the NAS file server bridged older and newer technologies. "That's a big plus for us," says ITOS director William Bell. "While our Unix workstations are older, the software is more stable than NT, so the NAS server enables us to tie it all together and generate better performance."
Nellis Air Force Base
As a senior systems engineer at Nellis Air Force Base in North Las Vegas, Don Wells runs the IT department of a 5,000-person civil engineering (CE) squadron responsible for designing, building, and maintaining everything on the base from sewer pipes to aircraft hangars.
After building a small server farm following a migration away from a minicomputer, Wells and his IT staff were ready to consolidate and migrate to newer technologies, because the staff was spending too much time managing and adding capacity to older servers.
"I'm trying to simplify my job in a industry that has grown leaps and bounds beyond whatever we imagined, and the hardest thing for us to do is keep up with the technology," says Wells.
Wells chose a NetForce 100 NAS server from Procom Technology, which quickly scaled to serve files among divergent groups of engineers and builders. CAD/CAM data stored on the NetForce NAS device provides detailed maps illustrating all electrical, water, sewer, and telecommunications lines on the base. Accessing files directly over the network was important because different user groups with different platforms required access to the same information.
For example, if an engineer uses a CAD/CAM program to produce and store roadway plans on the NetForce 100, workers preparing to dig can access the plans without reconfiguring their client machine to access a particular server. As a result, Wells says considerable time can be shaved off a project.
Wells also found success using the NetForce 100 as an Intranet server. Without considerable effort, employees have access to personal storage space, home folders, and shared information.
"A tangible NAS benefit is that it gives the IT person all the functionality of a standard server environment, but without the overhead of administration," according to Wells, who says scaling capacity was one of his most time-consuming administrative duties. "Now, if I need more capacity, I don't buy another server; I buy more capacity and plug it in to my network. It only takes about 10 to 15 minutes of configuration.
Envision Media, a 14-person advertising agency in Soquel, CA, installed NAS devices last June to help solve several file access and storage issues.
As part of its client services, Envision creates Web sites and portals. In addition, the agency runs a mixed shop of Unix and Macintosh workstations for engineering, with business operations running applications stored on NT servers. The agency needed to share mixed files internally and with clients.
Sean Tabatabai, Envision's chief operating officer, recalls the agency was increasingly concerned about failures on its Windows NT server and the shortage of available disk space. With no formal IT department, they looked for a simple solution capable of communicating with a variety of desktop platforms. They also needed a device that could serve as a temporary backup device or as an intermediate repository to store or access data, should the server go down.
They chose two 30GB Snap servers from Quantum Corp., each of which took "about a minute" to configure, according to Tabatabai. He says the configuration was in dramatic contrast to adding storage in a Windows NT environment, which requires you to take down the server and modify the RAID array.
As the provider of the Web-based Personal Portable Network (PPN), eTunnels ironically uses NAS to supply NAS.
Through a desktop client interface, PPN subscribers can form personal networks from which network members access their files and data stored on the Internet.
eTunnels has the quintessential storage requirements of a startup e-commerce site. As more subscribers sign on and access data, its storage infrastructure had to scale up to handle increased traffic on the site.
As a company whose success hinges on constantly providing high-speed file access, eTunnels turned to a NAS device to lessen its dependence on its front-end servers and to provide a robust file server dedicated to retrieving subscriber data.
On the front end, eTunnels operates 10 SPARC-based servers linked across a 100-base-T network that processes subscriber inquiries. Through the NFS protocol, the front-end servers then access an Auspex Systems NS2000 NAS server, which stores about 500GB of PPN subscriber data.
Gersham Meharg, chief technology officer at eTunnels in Vancouver, Canada, said they considered taking "a more traditional approach" of buying a Sun SPARC server, adding a RAID array, and sharing files. The IT staff also weighed whether to add more SPARC servers and string together a series of Linux servers running SAMBA or NFS protocols.
With subscribers being added daily, Meharg said while evaluating the NS2000 they became sold on the NAS server's ability to easily scale capacity to meet subscriber demand. While the NS2000 currently holds about 500GB, it's capable of scaling to 8TB.
"Some of the stuff we're doing is fairly intensive on the host processor that's actually talking to the clients," says Meharg. "So we saw a need to separate that functionality and have a NAS device in the background talking to our front-end processors, which are talking to the subscribers," Meharg says.
Isdaner & Co.
With 50 workstations and a fleet of remote laptop users running NetWare and Windows NT, the accounting firm Isdaner & Co. LLC, in Bala-Cynwyd, PA, was running out of space on its Windows NT server.
Already taxed with a slew of projects, the firm's three-person IT staff was concerned about having enough time to install and configure another server, add users, and manage user licenses. Isdaner chose Hewlett-Packard's 30GB HD4000 NAS server, in large part because of low administration requirements.
"Administration is a big issue because there's literally a hundred other projects that our IS staff are involved in. Layering in more administration while attending to the other IS needs of a growing office was not something we wanted to encounter," says Mark Green, Isdaner's manager of information services.
An Isdaner & Co. policy mandates that laptop users take daily snapshot copies of their data while at a client site. The HD4000 proved useful as a data repository as accountants downloaded their data. Back in the office, through Microsoft's Network Neighborhood, employees now directly access the remotely gathered information on the network without considerable time spent configuring menus and custom controls.
Peerless enables NetWare NAS
By Dave Simpson
Targeting OEMs of NAS devices (or "appliances"), Peerless Systems last month shipped code that provides embedded support for directory services and enables secure management and connection of NAS devices.
The initial version of the Embedded Directory Agent (EDA) for Storage software is aimed at NetWare NAS environments, but future versions could be used to manage network devices in Windows 2000 and SAN environments, according to Peerless vice president and general manager Adam Au.
Procom Technology is the first licensee of the NetWare 5.0 version of EDA, but Peerless hopes NetWare 4.0-compatible code OEMs will embrace the new version. Those vendors include NAS vendors Alcita, Allion America, Axis Communications, Maxtor (Creative Design Solutions), Micro Test, and Quantum (Meridian Data).
EDA is compatible with Novell's NDS eDirectory; future versions will be compatible with other LDAP directories such as Microsoft's Active Directory and Netscape's directory. With EDA enabled, NAS devices can act as directory clients, and appear as objects in the directory tree.
NAS product classes defined
By Farid Neema
Generally, there are three classes of network-attached storage (NAS) devices. However, no hard boundaries exist between the product classes, and the definition evolves with time as additional features are made affordable by advances in technology.
A class-1 product is resistant to the most common failures (such as disk drive, power supply, and cooling system), but it is still vulnerable to less common component failures, and usually must be turned off for planned maintenance. Its connectivity is limited to one topology (Ethernet, for example) and one file system (such as NFS).
Examples of class-1 NAS vendors include Axis Communications, Maxtor (through its acquisition of Creative Design Solutions), and Quantum (via its acquisition of Meridian Data.
A class-2 product has no single point of failure and allows all field-replaceable units to be swapped while the system continues to operate. It incorporates some performance features, such as faster write for RAID configurations, complex caching algorithms, and/or dedicated data paths. The system can be scaled many ways, allowing easy growth in performance, resiliency, and connectivity.
Integrated backup is usually offered as an option, and administration of all network-connected storage can be performed from one central location.
Examples of class-2 NAS vendors include Hewlett-Packard, LSI Logic, Network Appliance, Procom, and Unisys.
Features of a class-3 product include connectivity to several topologies and network file systems, sometimes extending to proprietary systems and mainframes. Performance is improved through automatic load and path balancing, and high-speed transfers between storage domains assigned to different file or application servers. Accessibility is enhanced by a feature that ensures disaster protection. Failing components are diagnosed, reported to a remote service site, and eventually corrected or replaced before they become inoperative. Disk drives can be scaled to very high capacities (over one terabyte) within an enclosure, and capacity may extend beyond the box to include other storage systems. Storage management features extend beyond backup, to include applications such as archiving, library management, and hierarchical storage management (HSM).
Examples of class-3 NAS vendors include Auspex, EMC, IBM, and Network Appliance.
Farid Neema is president of Peripheral Concepts Inc., a storage market research and consulting firm in Santa Barbara, CA.