After a reader sent a note concerned over a comment on Quantum Atlas III/Viking II 'AV' tuned drives not being recommended for mission critical data storage I wrote my contact at Quantum. A complete explanation of the issue follows:

" Mike,
Atlas-III and Viking-II are no longer our latest line of high end SCSI drives. Please visit our web site at www.quantum.com for information on our latest high end scsi offerings (Atlas-IV & Atlas-10k). While all the test data is not yet in, the increased performance of these latest products are showing signs of crisp video playback with no dropped frames (@~>30fps) in their unaltered generic factory configuration.

The ad referenced below is true to the extent that you bought "A/V Optimized" drives from an authorized Quantum distributor. Those drives will have a special label on them indicating that they have been optimized for use in an AV Environment and should not be used in environments where data integrity is required. In a nutshell Mike, the previous generation high end drives were NOT designed for the Digital Video market but for workstations and servers. Consequently, the drive error recovery code algorithms would go to extraordinary lengths to return the data that was written with 100% accuracy.

In the AV world, 1bit in error (which I believe was the spec for each 10e6 bits read) was hardly worth fighting for; it could be described as a shift in the shade of gray of one pixel in one video frame. On the rare occasion an error was encountered, the Atlas-III and Viking-II would tunnel through it's error recovery routines until it corrected the bit in error which in an AV application could cause a dropped video frame (this would only happen when the production company was showing the finished work to their client, of course!).

So, Quantum went to great lengths to try and come up with a solution to this problem, and, short of redesigning the product there were several things we could do to help alleviate the "dropped frame" phenomena on the Atlas-III and Viking-II products, one of which (don't really want to reveal all our secrets!) was to manage the error recovery differently, which addresses your email.

Going back to the design engineers, we learned as much as we could about error recovery mgmt and then produced a utility that basically "turned down" error recovery retries. The big problem we were then faced with is exactly as your email points to below; while we found a work around for the video guys who were using the Atlas-III and Viking-II in a video environment, we needed to make users aware that with these Quantum drives, video optimization meant basically reduced error recovery capability. So again, to the video user, one pixel gray shade error is almost meaningless, but, a label had to go on the drive to prevent it from being re-deployed into any application that required maximum data integrity. Please note here that an AV Optimized Atlas-III or Viking-II still has error detection and correction capability but for error correction retries, to a lesser degree. What does this mean? It means that if a drive develops read problems, and can't correct them within ~50ms, it will fault and will need to be replaced.

Incidentally, this software was made available only to trained Quantum Authorized Distributors who were responsible to train their customers as well. It was never intended to be made available to the general public. And, optimized drives are recommended for use only for video data. As for MAC's, I'm not sure how an optimized drive would find it's way into a MAC, certainly not OEM. And, MAC drivers would not affect the Quantum drive unless they specifically went in and modified the drives mode pages, as you suggest, in which case all bets are off!

Lastly, Quantum took a long hard serious look at the demands of the video market and have incorporated many new features into our latest high end Atlas-IV (7200rpm) and more specifically, the Atlas-10k (10,000rpm) SCSI drives that allow for uninterrupted video playback performance without compromise to data integrity or the need for customization. The performance of 10,000 rpm appears to be the key ingredient for AV applications with 5mS access time and under certain workloads > double the average throughput of the Atlas-III/Viking-II.

If you use or have an interest in High End Quantum SCSI drives for Video Applications, please watch the A/V section of our web site for collateral information on how well our new products are performing in the AV environment - I'm sure there's not much out there at the moment on the Atlas-IV and Atlas-10k drives but I don't think it will take marketing long to get that info posted once it's available. The feedback we are getting on our latest SCSI HDD's from video users is so good it makes us blush!

-Mike, sorry for the verbose reply however I sensed the concern in your note and felt it warranted a thorough explanation. If you have further concerns, don't hesitate to contact Quantum.
Best Regards,
John Millette
Quantum Field Engineering. "