Videography - August 1999

SGI and Prisa Build SAN Castles Together
By Sheldon Liebman

Over the past few years, moving video around a facility has undergone a fundamental change and we at Videography have spent a lot of time keeping you up to speed on those changes (if you'll pardon the pun). Instead of a traditional video network, many broadcasters and production facilities have shifted to using computer files and digital data that are moved from location to location using a fast network.

The networking choices in this area are vast and include one or more versions of ATM, Ethernet, Fibre Channel, HIPPI, SCSI, SSA and more. The positives and negatives or each format have made it difficult to choose a single type of network, and a lot of you have implemented multiple networking schemes as a way to "hedge your bets."

Throughout this whole process, the supporters of Fibre Channel pointed to many factors that they believed were destined to make it the networking protocol of choice. However, a lack of interoperability between network types and equipment from multiple manufacturers was a stumbling block that stood in the way for many people and companies. It appears that those blocks are finally being removed and Fibre Channel can finally declare victory. As part of the victory celebration (or perhaps as the reason for it), SGI and Prisa have formed a partnership to deliver Fibre Channel-based SANs to SGI customers.

Multiple Choices, Maximum Flexibility
From the beginning, Fibre Channel was designed for use with three different network topologies. The Fibre Channel standard supports both computers and storage devices as nodes on a network. As a result, you can connect storage directly to a single computer as a substitute for, or in addition to, traditional SCSI connections. This type of arrangement is called a Point-to-Point configuration and provides faster speeds and longer distances that SCSI.

With Fibre Channel, you can have at least 30 meters between devices, which is significantly farther than is possible with SCSI. On the speed side, a lot depends on the drives and controllers being used. However, Fibre Channel connections can provide burst speeds up to 200 MegaBytes per Second (MBps) and sustained rates of over 50 MBps. Even the most advanced SCSI devices available today don't support these speeds.

The next type of Fibre Channel topology is Fibre Channel Arbitrated Loop or FC-AL. It is very well suited for small clusters of workstations and storage and has become one of the building blocks on which Storage Area Networks (SANs) are built. Using FC-AL, a Fibre Channel network can be configured at a lower cost than if a full blown switch-based fabric is created.

The disadvantage of FC-AL, however, is that all of the devices share the network bandwidth and performance degrades after a certain number of devices are connected. One way around this is creating multiple loops based on workflow requirements and connecting those loops together. When information needs to pass between the loops, however, the performance may degrade.

For large networks, the best method of sharing information involves using one or more switches to connect your devices. This configuration is also supported through Fibre Channel and represents the original intention of the standard.

The difference between a switched network and one that uses hubs is a complete story in itself, so only a short answer will be presented here. Basically, a switch has intelligence and communicates with every device connected to it. This results in a significant performance increase, although at a much higher price. A hub, on the other hand, is not an intelligent device. Basically, it connects all of the devices to a single pipe and lets them determine on their own how to move data between them.

Mix and Match
One of the more recent developments in the Fibre Channel puzzle has been the creation of Fibre Channel switches that can also be linked to FC-AL configurations. This is called Fabric to Loop, or FL, and it allows companies to invest in FC-AL today and upgrade to a switched fabric tomorrow. Prisa Networks has invested a lot of time and energy to become one of the first companies to take advantage of this upgrade path, especially when used with Silicon Graphics workstations.

And the Winner Is...
The information presented above provides some background on why many people predicted that Fibre Channel would eventually "win," but SGI and Prisa have actually helped it cross the finish line.

Early adopters of Fibre Channel included HP and Tektronix, who built their video server business around Fibre Channel connectivity (although now HP's servers have been sold to Pinnacle and Tek has spun off their Profile business). Although this provided a lot of the early momentum, it wasn't really enough to push Fibre Channel over the top. To do that, SGI had to get involved along with a couple of other big players.

At the component level, IBM recently developed native Fibre Channel disk drives, which the company avoided for a long time. Instead, IBM focused on SSA as the future of high-speed networks. This move to build and sell Fibre Channel drives is a strong sign that one of the largest disk drive suppliers in the world believes that Fibre Channel is the future.

At the software and system level, Avid Technology has announced Unity, a new family of shared storage and distributed computing products for digital post-production environments. At the core of Unity is Avid Unity MediaNet, a platform independent set of capabilities for file management and data sharing. Although the system supports multiple types of high-speed networks, the network interface card included with the system is a Fibre Channel NIC.

Getting to Know You
And, of course, there is the partnership between SGI and Prisa. Last December, Silicon Graphics announced that Prisa was the first networking vendor to participate in its Bandwidth Solutions program. This program recognizes best-of-class, third party products that have are tested and fully supported on SGI platforms.

Although their selection in the Bandwidth Solutions program is less than 9 months old, Prisa and SGI actually have a long history together. Since it's founding five years ago, Prisa has concentrated on creating Fibre Channel products for SGI workstations. It is the only company that provides 64-bit Fibre Channel adapters for SGI's HIO, GIO, XIO and PCI bus computers. Prisa also markets a 32-bit adapter for Windows NT servers and other computers utilizing a 32-bit PCI bus. Since SGI is marketing Windows NT workstations at this point, a good fit is now even better.

Perhaps the most interesting aspect of this program is how the companies are working together. SGI's global sales force can now sell turnkey SANs to their customers, which SGI installs and supports in the field. Once an order is received, however, the SANs are built and tested in Prisa's headquarters in San Diego. To ensure that they work correctly, Prisa has a test lab that basically includes every type of workstation an SGI customer could connect to a SAN. On July 14, a Prisa announcement confirmed that this process is in place and customer shipments have started.

The result is that an informal arrangement is now a formal one and both companies reap the benefits. Prisa has always relied heavily on SGI to refer customers to them and now everyone in SGI has an added incentive to do just that. As a result, Prisa doesn't need to worry about building its own global sales organization.

At the same time, SGI gains immediate expertise in creating, testing and managing Fibre Channel SANs through Prisa. In one of the few examples of a truly win-win-win situation, SGI's customers gain the ability to install state-of-the-art SANs without having to worry about who will support them in the field.

Over time, Prisa will be able to shift away from the hardware business and concentrate solely on the software side of the equation. SGI's hardware strength can be used to manufacture the networking hardware and Prisa can create all the tools necessary to manage and optimize the network. It's a plan that both companies are comfortable with and should work well for customers also.

Although the network war isn't completely over, Fibre Channel has become the method of choice for moving video files at high speed. As a result, SGI and Prisa are going to spend a long time building castles in the SAN.

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