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What is Wide Area File Services?

Wikipedia definition: "Wide Area File Services (WAFS) products allow remote office users to access and share files globally at LAN speeds over the WAN. Distributed enterprises that deploy WAFS and WAN optimization solutions are able to consolidate storage to corporate datacenters, eliminating the need to backup and manage data that previously resided in their remote offices. WAFS uses techniques such as CIFS and MAPI protocol optimization, data compression, and sometimes storing recurrent data patterns in a local cache."

Wide Area File Services (WAFS) refer to technologies that enable the consolidation of file servers from remote sites to the data center without compromising end user performance. While WAFS can be a useful tool for many users, it is only a part of the total remote office solution that most enterprises are seeking.

WAN Acceleration Technology Overview Video

While WAFS solutions address bandwidth and application performance problems associated with file sharing, the typical enterprise has a heterogeneous mix of data and applications moving across its network to remote sites. The types of data include SSL, email, web-based enterprise applications, database applications, ERP, FTP, backup and replication, proprietary applications, and more.

WAFS appliances - a type of caching solution - work by storing copies of files that have been accessed over a WAN in local devices, so that subsequent users get accelerated performance. A WAFS only solution however has serious limitations. The table below offers a comparison of some of the more important differences between a WAFS only approach, and Riverbed's WAN acceleration solution.

	WAFS Appliances	Steelhead Appliances
Applications Supported	File Systems	All TCP traffic
	Limited Email Support
Mechanisms	Cache copies of files	Application-independent data store
	Some support for email attachments	Application-specific latency optimizations
		Multiple TCP optimizations
Bandwidth Optimization	Only when cached files are requested	All TCP Traffic - typical reduction in overall WAN traffic is 60-95%
	Some support for email caching
Support for Disconnected Operation	Yes	Yes
Proxy for File Server	Yes	No
Transparent to Clients and Servers	No	Yes

Wide area file services can serve an important function for organizations looking to accelerate consolidated file servers. But WAFS comes with a number of limitations that are essential for every organization to understand:

• WAFS is limited to file sharing. WAFS products can only cache files that are sent over the WAN via application protocols they know, which means that they are limited primarily to CIFS and NFS caching.
• WAFS cannot deal efficiently with some changes to data. In the event of a change of file name or a move of a file from one directory to another, WAFS products typically require the complete file to once again be transferred across the WAN. This severely limits application performance optimization under many common use cases.
• WAFS keeps multiple file copies. The way WAFS operates, it must store many copies of a particular file throughout the network inorder to accelerate performance. Not only is this a security risk, but it can lead to versioning problems whereby users in different locations are accessing the different version of the same file.
• WAFS is not designed for Disaster Recovery. Because WAFS functions by short-circuiting the typical communications processes of applications, it does not help in Disaster Recovery scenarios. It also lacks any meaningful application protocol optimization in order to accelerate the performance of Disaster Recovery applications.
• WAFS may not ease IT management. WAFS is generally designed on top of windows servers. Instead of creating a true appliance design, WAFS appliances require IT managers to put the same amount of effort into managing WAFS servers as they would any other remote server.

Learn more about WAN Optimization: watch Jack's story...

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