Tip TOEing through NAS

Over the past year, network-attached storage has gotten quite the shot in the arm. In an effort to address common customer concerns, both chip and NAS vendors have come together to provide one more step along the evolutionary path to serving files in a high-performance and scalable environment. This is the first of three articles that will discuss how the NAS environment is changing to take advantage of emerging technologies.

One of the main detractors, we all hear, to providing any type of high performance storage access over the traditional data network is the overhead that is required to process the data through the TCP/IP stack.  This is the case for both NAS storage (NFS and CIFS) and iSCSI SAN storage access.

Over the past year, chip companies, like Alacritech, have brought TCP offload engines (TOE) to market.  TOEs move the processing of the TCP/IP stack out of the operating system software and onto a network interface card (NIC) that plugs into a server. This hardware implementation both increases the rate at which TCP traffic can be processed and reduces the amount of processing cycles on the server.

Sounds great, right? Well, it turns out that TOE technology is not “quite” ready for general systems usage yet. This is due to the fact that every operating systems vendor and TOE developer implements their TPC/IP stack a little differently. Today, operating system vendors must write a significant amount of special (custom) code to interface with each TOE vendor’s card (not likely, I hear you saying). At this point in time, this also means that one operating system would not be able to support two vendors’ cards simultaneously in a system. What this means to the end user is that the TOE vendors and the systems vendors must get together, agree upon, and develop common (standard) interfaces between the operating system and the TOE. It will be a while before generalized TOE cards are available at Comp USA or Fry’s Electronics. However, don’t be surprised to hear your NAS and even systems vendors claiming increased performance for your network data traffic, especially in markets that require large amounts of data to be transferred across the wire.

NAS appliances have long been sold as systems that “specialize” in serving file data to applications.  These appliances already have operating system changes to make file access more efficient. It makes sense then, that the NAS environment is the first market to gain significant value from implementing TOEs.  Yes, the implementation is custom, but who cares, almost everything else about the system is custom as well. All the customer sees is their data is moving more quickly.  This is especially true for companies that have the requirement to share very large files, such as medical images or video streams.

Just when you thought your NAS vendor had squeezed all the performance they could out of their implementations, chip vendors have introduced a new tool that can provide even greater performance. Alacritech, Qlogic, and Adaptec are just a few of the companies working to produce TOEs that will increase the performance of storage access across the traditional data network.

Next week, I will look at how server cluster technologies are being evolved and used to provide NAS scalability.