BY DAVE SIMPSON
A number of companies have implemented a relatively new category of products that one consulting firm—the Taneja Group—refers to as wide area file services (WAFS) appliances, which significantly speed up file transfers over WANs.
Other vendors that the Taneja Group includes in the WAFS category include DiskSites, Riverbed Technology, and Tacit Networks.
WAFS implementations range from relatively simple configurations that solve a single problem to more--complex implementations that tackle a variety of problems.
Wide area file service architectures encompass central servers and edge file gateways connected over a WAN.
For example, Decker Sabatini, an architectural firm, was experiencing crippling latency delays when it was trying to access files between its Albuquerque, NM, headquarters and Las Vegas branch offices. The company was using a dedicated point-to-point T1 line, but it often took more than five minutes to open 2MB to 3MB AutoCAD files from the remote location when multiple users were working on a file simultaneously. After Decker Sabatini installed a WAFS appliance from Tacit Networks at each site, that operation now takes only 15 to 20 seconds, according to Gregor Wells, IT manager at Decker Sabatini. In fact, Wells says that it's almost as fast as LAN-based file access.
In the Decker Sabatini setup, the Tacit appliances serve files from remote locations to local clients using caching and other techniques. Tacit's WAN-optimized protocol, which is part of the company's Wellspring architecture, connects to CIFS and NFS file systems and includes six software technologies: differencing, data streaming, compression, data aggregation, I/O clustering, and read-ahead functionality.
To solve the latency issues with its T1 line, Decker Sabatini also considered protocol optimization devices, but those devices did not cache data at remote sites. The Tacit appliances perform both functions, as well as synchronizing (and locking) files to keep all the files up-to-date.
In a more complex configuration, Gensler Architecture, Design and Planning Worldwide, has installed 13 Steelhead appliances from Riverbed Technology—six appliances at its local offices in San Francisco and seven appliances at regional offices. The architectural firm plans to eventually install the appliances at all 26 of its regional offices across North America and Asia.
Prior to installing Riverbed's Steelhead appliances, Gensler used T1 lines to replicate blueprint files between sites over a WAN. In addition to the same latency problems encountered by Decker Sabatini, this approach led to severe management and coordination problems, according to Bruce Bartolf, Gensler's chief technology officer. In fact, he says that sending files via overnight courier was often the most efficient way to share files because of the expense and latency issues associated with the T1 links.
The result was that the firm was unable to work collaboratively in a distributed environment, and Bartolf says that the primary advantage of deploying the Steelhead appliances was the elimination of this problem.
Gensler is now getting from 25Mbps to 40Mbps file-transfer speeds vs. 420Kbps without Riverbed's Steelhead appliances, a performance improvement of 60x to 95x. Additional benefits include cache coordination/management, zero management overhead, and up to an 81% reduction in the amount of data that has to be transferred due to pattern caching, which significantly reduced bandwidth costs, according to Bartolf.
Eventually, Gensler plans to remove its primary storage (as well as backup hardware and software) from its remote offices and consolidate/centralize virtually all storage at its headquarters, one of the key potential benefits of WAFS appliances.
According to the Taneja Group, WAFS appliances and software consolidate distributed file storage in a centralized location and intelligently provide fast ("same as LAN") access to files over a WAN through gateways at remote locations. WAFS appliances reduce the latency inherent in WANs while maximizing bandwidth. In some cases, WAFS appliances allow geographically dispersed corporations to eliminate storage equipment (and files) at remote sites and centralize storage operations at a primary site, giving IT managers better control over corporate data.
The Taneja Group likens WAFS appliances to intelligent file-caching nodes that are analogous to Web caches that improve performance for static content delivery at the "edge" of the Internet. However, WAFS appliances also address challenges such as block- and segment-level transfer management, CIFS and NFS protocol optimization, read and write caching, and data-contention resolution.
In a white paper on the subject (www.tanejagroup.com), the Taneja Group goes on to describe the benefits of WAFS: "The real value in wide area file services takes place back in the corporate data center where the gateways 'fan-in' to a central server, which typically interfaces with a standard file server or NAS head, providing consolidated storage capacity to the entire distributed environment. With the 'master copy' of all data stored centrally, the remote sites no longer need to have file servers or tape backup solutions deployed in each location. The result is that data and storage is consolidated, but remote users still have the benefit of local file services." Additional benefits include better data protection and a more efficient method of addressing regulatory compliance.
Arun Taneja, consulting analyst and founder of the Taneja Group, adds that WAFS technology is a subset of what he terms distributed systems optimization (DSO) technology, which he defines as including features such as compression, protocol optimization, application protocol optimization, and Web/mail/file caching. Taneja includes Riverbed in the DSO camp.
For end users considering WAFS implementation, the Taneja Group recommends a number of evaluation criteria, including centralized management, integrity controls (which involves data coherency, data concurrency, and data assurance), Windows/CIFS support in addition to support for NFS, security controls, reliability (including clustering, fail-over, and hardware redundancy), and scalability.
In addition to Cisco's acquisition of Actona, there is further evidence that the WAFS market is poised for takeoff. For example, Tacit Networks has a reseller partnership with IBM, and Riverbed partners with EMC via EMC's NAS partner program.
For more information about WAFS, see "Wide area file services tame the distributed enterprise," InfoStor, April 2004, p. 30. The article can also be accessed at www.infostor.com.