RAID, NAS Combo Meets Demands Of Video Delivery

when AT&T Broadband bought a local cable company in Dallas, engineers oversaw a room full of Sony VHS players with as many as 40 machines operating simultaneously. The equipment was expensive and the rigorous usage required extensive maintenance. "Highly skilled employees were in the building round-the-clock inserting tapes and watching them spin," says Ron Rieke, chairman and CEO of R.A.R.E. Systems (Houston), a manufacturer and integrator of mass storage solutions.

The expense could have been justified if it had resulted in a more efficient system, but that was not the case. In addition to potential breakdowns, using VHS tapes holds the possibility of human error. The wrong tape can be played, causing further delays as tapes are requeued. VHS tape also has a short life expectancy. In addition to degrading over time, the tape is worn by constant winding over the heads of the player.

RAID Supports Reruns Indefinitely
AT&T Broadband looked for a way to improve its video storage and retrieval. An Internet search turned up the name of R.A.R.E. Systems, and Rieke was called in for a consultation. He designed a system that included 2 TB Infortrend RAID (redundant array of independent disks) array managed by Infortrend active-active controllers. As long as the speed and capacity are appropriate to the application, a RAID array can preserve data indefinitely as disks can be added or replaced.

However, RAID doesn't fully address the challenge of delivering huge files quickly. (A properly compressed full-length movie is around 4 GB in normal mode.) To solve this problem, Rieke incorporated R.A.R.E.'s RAZOR NAS (network attached storage) engine to act as a "delivery and control officer." The NAS appliance has SCSI or Fibre Channel ports connecting it to the RAID array and Gb (gigabit) ports at the other end. Network servers of any platform can connect to the NAS appliance through these ports for data delivery. The NAS appliance often handles 24 or more video streams simultaneously as the system is used to schedule, play back, and automate video over the network.

10 Gb Switches Open Door For Potential Upgrades
AT&T continued to operate with 2 TB of capacity for about six months, but as more files were converted to digital and the company gained confidence in the system's effectiveness, its storage needs grew. At that point, the cable company upgraded to 6 TB and may expand further.

Ironically, as the capacity and speed of the upgraded equipment increases, the physical size of the hardware shrinks. The first 2 TB installed in 2000 required a 76-inch-high cabinet. The most recent upgrade tripled the capacity and shrunk the cabinet to 10.5 inches. If AT&T chose to upgrade right now, Rieke says the next version would quadruple the capacity in the same space.

In addition to possibly increasing capacity, Rieke is anticipating increases in speed in the near future. Currently, the system is running on a duplex 1 Gb switch. "10 Gb is available only in the backbone right now, but 10 Gb switches are coming," says Rieke. "By early 2002, they'll be available in a card form that an integrator can just plug in, and I will be recommending them to my video customers."

AT&T's data continues to grow at an exponential rate, despite the fact that it routinely retires unnecessary files. Some are given a life expectancy based on how long they are expected to be valuable. Those that are to be saved indefinitely, but not accessed frequently, are migrated on a regular basis to AIT (advanced intelligent tape). This media has a capacity of 50 GB to 100 GB.

Rieke's research indicates that the overall cable industry represents about a $12 billion market for upgrade expenditures. He believes this configuration would also be viable in long distance medical or learning applications, government offices as their operations go paperless, broadcast TV, and anywhere else large complex images are a part of everyday operations.