Gold's Gym had been asking its network and end users to do some heavy lifting. End users trying to work together across 40 gyms and three corporate offices were using e-mail to exchange files, and faced the challenge of keeping track of changes to different versions as well, said Kurt Koenig, the fitness company's IT manager.

But that system wasn't sustainable, Koenig added. He wanted to relocate files previously housed at each location to a centrally accessible data centre. To make the transition, he turned to an increasingly popular technology called wide-area file services (WAFS), designed to provide LAN-like file delivery across WANs.

"We now have one G: drive with national access, so no matter where users are, they can get to their data quickly" he said.

Gold's is using a WAFS product from Availl Software, one of a number of vendors in this market, a list which also includes Brocade, Cisco and Swan Labs. WAFS products come in the form of appliances or as software to run on file servers.

WAFS works by reducing the chattiness of the Microsoft CIFS (Common Internet File System) and Unix/Linux NFS (Network File System) protocols. It also works by decreasing the latency of WAN communications by eliminating much of the round-trip traffic caused by opening and closing files. CIFS and NFS were designed to work in LAN environments where latency is low.

"The CIFS and NFS file protocols are extraordinarily chatty," said John Henze, director of product marketing for the Caching Services Business Unit at Cisco. "These files consist of hundreds and hundreds of synchronous, short byte-length messages that go back and forth before any payload is actually sent, causing high latency and low throughput. This differs from on the LAN where you have virtually no latency."

Seeking a way to centralise
Brian Laska, technical architect at Computer Sciences' Consulting Group/Global Infrastructure Services in Massachusetts, chose Cisco's File Engine after discovering and evaluating the problems with transferring files across the WAN.

"When we went to upgrade our server hardware to support Windows 2000, we saw that about 20 smaller branch offices were primarily doing file services," he said. "We wanted a way to centralise them, to support them, back them up and save on data-vaulting expenses. But we saw that centralising file services would be a heavy load on the WAN. The file protocols that are in use are not very tolerant to high latency, low bandwidth, wide area networks, which is what most companies have."

With the number of remote offices increasing, more and more data is transported across the WAN. Randy Kerns, an independent storage analyst in Colorado, estimates that Fortune 500 companies have as many as 4 million employees working from remote locations.

Further, many of these workers use file and print sharing extensively. Often, no skilled IT staff is available to handle operations such as network management and data backup. All of which adds up to a need for products along the lines of what the WAFS vendors are offering.

How it works
The software from Availl being used by Gold's Gym differs from appliance-based packages. In an Availl implementation, the software is installed on each Windows fileserver in the remote office and at the data centre. As users make changes to files, they are replicated to the data centre. As it is with most WAFS software, updated files are transferred to the remote offices only when requested.

In a typical WAFS configuration, an appliance is installed in the data centre, where it connects to primary storage. This appliance connects over the IP network with an appliance situated in the branch office. Users' requests for files are transmitted to the appliance in the data centre, and the file is opened and sent to the branch office. Changes that the users make to the file are similarly encrypted, compressed and sent to centralised storage whenever they are made.

In this fashion, IT can reduce much of the bandwidth required by file operations. Users also can benefit from the centralised management of file data on the WAN. And because data from remote offices converges at the data centre, it's no longer necessary to back up the remote.

Some WAFS appliances, such as Tacit Network's iShared Remote, or Accelerator from Expand Networks, have local cache memory, which holds frequently accessed files so they can be instantly available to remote office users. File server-based software, such as Availl's, synchronises all file changes with the data centre and other remote offices.

Other advantages of WAFS
Much WAFS software has coherency, file locking and consistency checks to prevent files from overwriting those that users are working on and ensure the most current version is the one users access.

In some ways, WAFS offerings sound like WAN acceleration products, and in fact, vendors are increasingly offering dual-purpose products. Last week, Expand, a Web-optimisation vendor, announced a product called Accelerator that handles WAFS; Swan Labs last month unveiled an appliance called WANJet, which it says cuts WAFS traffic by as much as 500 percent; and Riverbed Technology, which makes the Steelhead line of accelerators, last month announced software that supports WAFS.

WAFS deals with file data - Word documents, spreadsheets, Microsoft Exchange data, while WAN acceleration or optimisation appliances work with other forms of data - HTML, HTTP, DNS and VoIP.

"File services are absolutely a huge piece of it and a pretty big pain point," Henze said. "But there's a whole lot of other traffic going on across a distributed environment, such as HTTPS, HTTP, FTP, messaging [MAPI] or voice over IP."

Cisco's FE 511 File Engine handles WAFS, but don't be surprised to see Cisco offer an integrated WAFS and WAN acceleration product. After all, the company recently bought FineGround, which specialises in application acceleration, management and security.