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The decision to install a network may be easy enough, but there are a lot of variations on the network theme. Variables include the kind of cabling (copper or fiber), the switches, the type of storage and the network protocol. Perhaps most important, however, is the overall system architecture.
Bacorn says the most common configuration in general use is the Local Area Network (LAN). “This is typically Ethernet-based,” he explains, “using either 10BaseT, 100- BaseT or Gigabit Ethernet. Ethernet is relatively inexpensive to install and maintain. But a LAN is designed as an interoffice communication network. Its primary use throughout the world is for e-mail, moving spreadsheets around or accessing the Internet. Though it can be used to move large files, it’s not recommended.”
One problem with Ethernet is that the actual throughput doesn’t measure up to the nominal bandwidth. “Ethernet has very high overhead,” Bacorn explains. “Rather than doing a simple file copy all at once, an Ethernet must run algorithms, calculate check sum and constantly monitor the transaction of each bit of data. This slows down the transfer enormously. Add in the fact that others are attempting to do the same thing, and you have a bottleneck. All copies slow to a crawl.”
Another difficulty, Bacorn points out, is that most DAWs will not work directly with a networked file. And all storage accessed through Ethernet is considered remote rather than local. “This means you have to copy a file to your desktop or local storage in order to use it,” Bacorn says. On large projects, allowing different users to download and alter files creates the need for version management, adding another layer of complexity.
For demanding studio applications, the favored alternative to an Ethernet LAN is a Fibre-Channel SAN. “At best, Ethernet is a stop-gap measure before the implementation of a Fibre-Channel network,” says Gary Holladay, chief systems engineer at Studio Network Solutions in St. Louis, Mo. The company markets a solution called A/V SAN, which Holladay says offers 64-track playback and record capabilities from a single SAN-based drive.
“Fibre-Channel offers more bandwidth than any other topology, in- cluding FireWire,” Holladay continues, “and it gives you more throughput than any DAW can handle at this point, 200 MB-per-second in full duplex. If you’re going to spend money on networking your facility, spend it on a technology that already has the bandwidth to sustain your studio for years.”
“High-end Fibre-Channel storage is ideal for audio post,” agrees Rorke, whose company makes the Rorke Data SAN. “Fibre-Channel bandwidth delivers the necessary data rates. It’s not just a matter of the overall sustained MB per second per user, but also the often-sporadic burst-rate requirements of multitrack environments.”
As described by Glyph, which sells a SAN solution called Coba/SAN, a SAN is a shared, high-speed storage network allowing multiple users to access different types of storage devices through secure management software. Hard disk storage is pooled for use by the entire work group, with each workstation accessing the storage as if the drives were local. That means a file created on one workstation is immediately available—depending on access privileges—to everyone else on the network.
In a typical setup, the SAN hardware and storage devices are located in a machine room, isolating production areas from drive noise. In each of the facility’s DAWs (and nonlinear video editing systems),
there is a Fibre-Channel host bus adapter (HBA) card. These are linked to the SAN hardware via fiber-optic cable. The SAN hardware is also hooked to SCSI or fiber drives, which may be RAID arrays (Redundant Array of Independent Disks), in which a number of hard disks are linked together as a single volume. The drive volume appears on the desktop as if it were local external storage.
The SAN architecture offers several advantages. “You eliminate the server,” Bacorn says. “Your system is working directly off the storage, and it sees the storage as local, which is required by most audio applications. Also, in a SAN the overhead is put directly on the Fibre-Channel adapter card. All checking and error correction is built into the hardware using FC protocol.”
Berger says The Village’s SAN makes life much easier for multiple users working on the same project. “We have had sessions that used three Pro Tools rigs in separate rooms working on the same movie. Two of them were doing offline editing and capture, and one was being used for mixing. They were able to exchange files and access the arrays very quickly. Another use is that the same client can go from room to room without having to transfer any files at all.”
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Reprinted with permission from
Magazine, June, 2001© 2000, Intertec Publishing, A Primedia Company All Rights Reserved
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