But, WAFS and WAN optimization products should be evaluated very carefully. Now that you've reviewed the essential issues involved in any backup acquisition, this guide focuses on specific considerations for WAFS and WAN optimization products. You'll also find a series of specifications to help make on-the-spot product comparisons between vendors, like Certeon Inc., Cisco Systems Inc., F5 Networks Inc., Juniper Networks Inc., Riverbed Technology Inc, Silver Peak Systems Inc. and more.
Consider the difference between product types and terms. WAFS products typically allow for continuous read-write access to centralized data, low latency and effective data transfer speeds similar to LAN speeds. By comparison, WAN optimization products use compression and data acceleration techniques to pass more data using less bandwidth. It's important to note that these products serve two distinctly different purposes. Some WAFS products include WAN optimization features, but it's not universal, and the two products can exist separately. Also, remember that vendors may rely upon their own unique definitions of these technologies. For example, Cisco calls this wide area application services (WAAS). Always perform a comprehensive review of features before making any product choice.
Consider the bandwidth and connectivity requirements. WAFS and WAN optimization products all rely on a WAN link, so understand exactly what types of WAN attributes the product will support. For example, some products may demand T1 connectivity, while other products may work over an ordinary Internet connection. Evaluate the level of bandwidth needed to support each remote office or location. As bandwidth costs increase, WAN optimization features can help to mitigate bandwidth requirements. It's also helpful to evaluate the supported transports, such as multiprotocol label switching (MPLS), IP VPN, satellite, frame relay, ATM or other supported transports to ensure that the product is fully compatible with your infrastructure.
Consider local caching and cache behavior. While connectivity and bandwidth are vital considerations, it may be even more important to evaluate the impact of connectivity loss. Generally speaking, WAFS works by retrieving files from the data center across a WAN and caching those files on local storage where users can access the data quickly. Changed files can then be sent back across the WAN to the data center as bandwidth allows. However, understand what happens when the WAN link is disrupted. Ideally, any files currently in the local cache will still be accessible, and the WAFS product will resynchronize its data with the data center once the WAN is restored. Also consider the impact of multiple iterations of a file -- recognize how the WAFS product handles multiple people working on the same file simultaneously and how WAN disruptions will affect those activities.
Consider data reduction techniques. WAN optimization applies compression and data reduction techniques to reduce the volume of data that needs to pass between the data center and remote location. For example, Availl Inc. claims a 95% reduction in traffic through byte-level differencing and compression. Cisco claims a 100-to-1 reduction in bandwidth utilization by eliminating redundant data and LZ compression. Citrix Systems Inc. claims an astonishing 3,500-to-1 reduction in data by applying a variety of compression/data reduction schemes. Data reduction will ideally reduce bandwidth requirements, but not all data compresses the same way. It's important to evaluate the techniques used in any prospective product, and gauge its effectiveness on your typical data volumes.
The WAFS and WAN optimization product specifications page in this chapter covers the following products: