Storage networks get help from WAN accelerators

Network World - Businesses looking to make consolidated storage networks perform better no longer need to turn to a single-purpose device for help.

Some vendors make single-purpose devices specifically for speeding up wide area file services (WAFS) such as Tacit's IShared, Cisco's File Engine and more recently FineGround's Velocity-FS gear.

But vendors that have been selling generalized WAN-optimization gear that improves many types of traffic now are tuning them specifically to handle WAFS traffic better.

For example, Peribit, Riverbed and Swan Labs address other types of traffic, as well as file sharing specifically. Expand Networks, whose gear performs a range of WAN optimization, says it has its version of file-sharing-enhancement software in beta tests.

Packeteer says it is on the verge of announcing a new compression algorithm specifically designed to reduce as much as possible the volume of traffic that needs to cross the WAN to transfer a file.

These devices have one thing in common. They intercept traffic flowing between clients and servers across the WAN and use varying methods to improve the response time that end users experience -- the goal being to make the interaction as LAN-like as possible.

The products try to improve how Microsoft's Common Internet File System (CIFS) and Network File System for Unix and Linux -- both designed for LANs and both very chatty protocols -- perform over the WAN, and the results can be dramatic.

Fentress Bradburn Architects of Denver improved the transfer time of certain files from a "painful" 10 minutes down to 10 seconds using Riverbed Steelhead appliances, according to IT manager Mike Rinken.

The devices have knowledge of CIFS that lets them predict the response a server or a client needs and to produce it locally rather than getting it from across the WAN. So for example, a local appliance will return acknowledgments for routine session creation rather than having the end machines send them.

This is similar to how Peribit's AppFlow works by predicting what response the protocol needs and supplying it locally.

These devices also cache patterns of traffic as it flows across the WAN. The next time one of these patterns appears, these appliances call out the cached version rather than tapping the server for it. The boxes also optimize TCP sessions between themselves to make transfers more efficient.

While WAFS is the hot application that these WAN optimization vendors are addressing now, look for them to home in on others, says Zeus Kerravala, vice president of enterprise networking at The Yankee Group. Riverbed, for instance, says it is