Tacit I-shared brings welcome relief to over-the-WAN file sharing

Sharing files with users at remote offices over a WAN often creates enormous headaches, due to limited bandwidth and the high latency of the connection, combined with the “chattiness” of file sharing protocols such as NFS and CIFS.

As a result, just making a quick change to, say, a Microsoft Office document, which usually takes mere seconds on a LAN or MAN (metropolitan area network), takes disproportionately longer over a WAN, thereby frustrating users and reducing productivity.

Unfortunately, intuitive remedies, such as improving the connection, usually cost a bunch and may not bring the expected relief. Alternatively, you can dramatically improve responsiveness by bringing copies of the files closer to the users at each remote location, but the effort of keeping versions consistent can easily nullify the benefit.

With that in mind, it’s not surprising that start-ups such as Actona, recently acquired by Cisco, and Tacit Networks have jumped on the opportunity to develop solutions that, using a complex mix of compression and buffering techniques, expedite file sharing over the WAN.

Since last year, Tacit has been offering a Linux-based version of its I-shared appliance, promising to “make the WAN disappear.” Recently, the company added a Windows NAS-based version that maintains the same architecture but adds improvements such as seamless installations in Microsoft shops, native support for CIFS, and the ability to enforce symmetric file sharing across the WAN.

After reviewing the new Windows-based I-shared 1.6.1, I have to admit that the appliance fulfills the promise of making remote file sharing fast and easy, and it doesn’t penalize customers with onerous housekeeping tasks.

Ready, set, WAN

To minimize logistics problems, I reviewed the I-shared on Tacit’s premises, on a dedicated test bed mimicking the typical WAN connection between a central office and a remote one. The central office setting included a Windows Server 2003 domain controller with Active Directories and a Windows 2000 file server hosting approximately 300MB of Microsoft Office files. To simulate remote users, I used two laptops running Windows XP Pro.

On the central office side, the I-shared box acted as a server cache; on the remote side, the second box was running the remote client on IBM xServer hardware. Both machines were running the Microsoft NAS software for Windows 2000, but the forthcoming version of I-shared, expected this month, should also support Windows Storage Server 2003.

To simulate the high latency and limited bandwidth typical of a WAN, I used an application developed by the Massachusetts Institute of Technology, Click Modular Router 1.3, running on a dedicated Linux machine. Using the solution, one can emulate WAN conditions by changing just two configuration parameters: Delay_Shaper to set the latency and Bandwidth_Shaper to set the connection speed.

Setup proved straightforward. Configuring the two I-shared appliances was easy, thanks to Tacit’s intuitive menu entries that are seamlessly integrated with the Microsoft NAS administrative GUI.

Instructing the I-shared server to inherit and propagate shared folders from my file server entailed simply typing the server name into the configuration menu.