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As far as cabling between the component parts of a network, the options are pretty straightforward. According to Sarig, it boils down to either CAT-5 wire with 100BaseT or two flavors of fiber-optic cable: 1000BaseT Gigabit Ethernet or Fibre-Channel.
There is a downside to fiber, but it’s financial rather than technical. “The major drawback is that each fiber ‘seat’ costs an arm and a leg,” Sarig says. “It’s much more expensive because of the need to move light. The switch usually has mechanical mirrors, which makes it very expensive—a typical switch can cost $20,000 to $25,000.”
Given the price tag, Perkins believes it’s wise to consider a facility’s requirements before committing to fiber. “For the average facility with two to 10 audio workstations, if the main thing you are trying to do is move around individual sound effects and music tracks, the money can be better spent [elsewhere],” he says. “But if you are dealing with video or trying to share Pro Tools projects, that might require Fibre-Channel.”
Perkins adds that, in addition to file size, the major consideration is how many concurrent users are expected to be moving audio files at a given time. “Even if you have 20 users,” he says, “if more than half of them are Avids that will only rarely be pulling audio, you may not need the strength of network required by a facility with seven Pro Tools and Fairlight users cranking continuously.”
Actually, the question of which approach to take is not strictly an either/or dilemma, because a Fibre-Channel SAN is generally in addition to, rather than in place of, an Ethernet LAN.
“You usually end up with a concurrent network of at least 100 -BaseT,” Sarig says, “because there is no good solution for TCP/IP traffic over a Fibre-Channel network. Es-pecially in large facilities, it’s very important that you do not let the e-mail and Internet server share the same LAN as your audio server. Also, in the case of fiber drives, there is the need for communication with the RAID resource allocation server, because the drives need to be ‘locked’ for write, meaning that many users can read, but usually only one can write at the same time.”
Sarig describes the outlines of a “combination network” that he says has worked out many times in the past. “You can have SCSI drives, which are cheap, and a SAN controller with Fibre-Channel connector, which is fast, and you get a sustained 25 MB per second. You can then decide to use it over a fiber switch, which is expensive, or hook it to a server and distribute over Gigabit Ethernet and 100BaseT, which is really cheap compared to a fiber network.
“It’s all a question of speed vs. dollars,” Sarig continues. “We have found that allocating a fiber RAID over a fiber switch just to push an average 20-second sound effect is not very cost-effective and usually not needed. However, to push 48 channels of full-bandwidth audio plus high-resolution video over 100BaseT is just not a good move.”
Driving for Speed
Of course, even the fastest network plumbing can’t guarantee that a system will perform at its fullest potential. “There are several factors that can affect the operation of a network,” Bacorn says. “Many stem from poor network design or running nonsupported applications, such as Beta software or pre-released products.”
Bacorn adds, however, that the most common reason for slow network access is simply the lack of enough drives. “If you think of the network as a car,” he says, “then the drive arrays are the engine. The larger or more powerful the engine, the faster the access time. The number of channels supported can range from 32 tracks to 64 and beyond, if you use the new 15,000 rpm drives.”
In addition to speed, reliability is a key consideration for drives. “We wanted our drives to be arrays,” Berger says, “because we had heard of clients’ drives getting corrupted and files lost, both from poor SCSI cabling issues and from not unmounting drives correctly. By switching to an array, we now have complete fault-tolerance—we are covered from any data loss, short of catastrophic failure.”
Berger says The Village’s storage design is completely redundant. “Every component has two power supplies, which have their own UPS backup. The drives are RAID-3 and have dynamic spares. We also back up the whole system daily to tape. We can assure the clients that all their data is both secure and safe at all times.”
The RAID approach also gives The Village some additional benefits. “We no longer have to do any disk allocation,” Berger says. “And when transferring files to a back-up set or a clients drive, the files we need are not spread out over several drives.”
As far as actually installing the network, construction is usually not an issue. “Cabling is a relatively easy installation process,” Bacorn says. “And most new facilities already have fiber optics installed. The storage is all installed in one location, typically the machine room. From that point, with the exception of the software and the HBA cards, the installation is complete.”
Berger adds that the location of the networking gear needs to be well thoughtout. “We had to make sure that we had ventilation to maintain an optimal…temperature for computer equipment,” he says. “We also had to make sure that we were able to hear any audible alarms. Because a failure would not bring the system down, we would need to know if the system required immediate attention. Using fiber gave us flexibility. We didn’t have to be centrally located in the facility, and we didn’t have to worry about any kind of external interference when installing the cables.”
Despite the many advantages of a Fibre-Channel SAN, Bacorn acknowledges that it’s not the right networking approach for all facilities. “Most could use one,” he says, “but there is a cost involved that some may find beyond their means. If you are looking for a SAN solution, however, don’t just purchase the cheapest. There are a number of SAN vendors in the world that sell on price, not functionality. Like anything that sounds too good to be true, it probably is, and your facility is not a good place to test a SAN.”
Philip De Lancie is Mix’s new technologies editor.
Reprinted with permission from
Magazine, June, 2001© 2000, Intertec Publishing, A Primedia Company All Rights Reserved
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