Giving VOD a Nod

Storage and software are key to successful deployment
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Every video-on-demand system starts with its server. That's the place content—a movie, say—is stored before being accessed by viewers. But when it comes to making the system work, it's the networking and software, not the size of the server, that makes a successful VOD deployment.

"There is much focus on server technology," says Yvette Kanouff, SeaChange corporate vice president of strategic planning, "but the key is the automation and making VOD happen seamlessly across the different areas of content access." Issues include error correction, whether the server integrates well with the content, and how the system scales out in terms of storage and ability to handle more subscribers.

Nothing makes Kanouff's point better than the fact that many of the VOD servers deployed in the U.S. have hard drives manufactured by Seagate, including the Cheetah 10K (which holds up to 292 GB) and the Cheetah 15K (which holds up to 146 GB). The drives are linked within servers to store the content.

Concurrent's MediaStore 1000 server has 14 Seagate drives with 73 or 146 GB of storage each. "The value we add," says Steve Necessary, president of Concurrent's VOD Division, "is in the software."

Rob Pait, Seagate director of global consumer electronics marketing, says that, although the Cheetah 15K drive has a smaller capacity, it offers the most performance for the dollar. The 15K name refers to the number of input and output actions it can handle per second. The more inputs and outputs the faster a VOD order can be executed and the sooner content can begin streaming to the viewer.

"The question," he explains, "is whether the VOD vendor wants good performance and outstanding capacity or outstanding performance and good capacity."

Just as important as the speed of the drives is the configuration of the system. The more components a system has, the more steps a VOD request needs to pass though before the transaction is complete and the greater the opportunity for a bad viewer experience, such as not being able to access content or place an order. Time Warner Cable, for example, created an "Interactive Services Architecture" that is used to help video servers, billing systems, and VOD and interactive-TV applications communicate. Both TWC and its partners changed their software so that there is greater interoperability, but it has come at a price: slower access and occasional hiccups.

Another configuration decision is whether to store content centrally or distribute it over multiple servers. A centralized approach lowers the costs associated with storage but increases the traffic and networking demands on the server. Distributing the content improves performance and, in the end, customer satisfaction but requires more storage.

A third approach is what Kanouff describes as hierarchical, with content stored on different servers depending on how often it's used. It's becoming popular with VOD operators. Storage is distributed more broadly, from content owner to MSO to headend, eliminating centralized storage. Says Kanouff, "Content will be streamed from massive server farms."

One wrinkle, however, is high-definition VOD. The large HDTV files require five times as much storage space as SD files. Solving that problem is important. "Right now, HDTV is more sizzle," Necessary says, "but, hopefully, it will be a real steak item in the future."

A popular way to increase capacity is to reduce the number of times a piece of content needs to be replicated across a system. nCube's HyperCube system is intended to accomplish that task by tying media hubs together, spreading the content across the different drives, according to Terri Richardson, vice president of product management, business development. As drives are added, the system continues to operate as one server.

"What's nice about the architecture is that, with two servers, the streams have two routes out of the system," says Christopher Brechin, nCube director of technical sales. Each time a disk is added to the system, approximately 30 streams' worth of capability are added. "The advantage," he explains, "is it prevents 'hot spots,'" where viewers can't access content.

Among the bells and whistles that help complicate a server purchase is SeaChange's VODLink feature, which allows an MSO to get content suppliers more involved by letting them build custom portals. CNN, for example, could build a VOD portal with a distinct CNN look. "There is more and more discussion about interfaces," Kanouff adds.

The challenge facing any MSO in purchasing a server is that VOD systems make apples-to-apples comparisons difficult. All systems have specific approaches to networking, interfaces, and storage that require more-complicated decisions than simply a checklist of needs.

But Kanouff suggests three basic things to do:

  • Look at all the technology, not just the hardware.
  • Check whether the system can be scaled up to accommodate services not yet developed.
  • Be sure of the financial security of the company.

"Most of the value in a VOD deployment lies in the software," Necessary points out. That will be even more important if video-on-demand becomes the business cable operators want it to be.

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