Fast Storage Without Those High SCSI Prices

Nonlinear video editing software and hardware have reached a price point that makes it possible for virtually any professional to own a system. And while the price of hard drives has been continuously dropping, video storage often requires more performance than the typical drives sold at the corner computer store can offer. If you are editing in DV, chances are that an Ultra IDE drive will be fast enough due to the compressed nature of the format. But those using other compression formats such as Motion JPEG or even uncompressed video are not so lucky.

In order to accommodate the throughput required by these systems, users have been forced to use very fast, AV-rated UW SCSI drives. The problem is that the price of these drives in considerably higher. As an example, a search for good deals on the Internet produced a 36.4GB 10,000rpm Seagate Cheetah for just under $500. On the other hand, a 40GB Ultra ATA/66 IDE drive was being sold for $130. Quite a difference, isn't it? And if you don't already have a SCSI controller card, expect to shell out a few extra hundred dollars.

Promise Technology offers many Ultra ATA RAID cards

When it came time to add yet another hard drive to one of my nonlinear editing systems, I decided to save some money and give one of the new IDE RAID controllers a try. Even though my Intergraph workstation came with a very fast SCSI controller, I had heard that with one of these IDE RAID cards you should be able to obtain the same type of performance you would expect from an ultra-fast SCSI drive, even when using a pair of generic 5,400rpm Ultra ATA/66 IDE drives. It sounded interesting, so I went for it.

The difference in cost was amazing. An ATA/66 IDE RAID controller card with a pair of 30GB drives, which the computer sees as a single 60GB drive, cost me just $350. I couldn't help being a little skeptical about the performance of such an inexpensive setup.

The IDE RAID controller that I purchased is a Promise Technology FastTrack66, which works with the cheaper Ultra ATA/66 drives. An Ultra ATA/100 version is also available. I purchased 5,400rpm hard drives instead of 7,200rpm ones, which would seem like a more logical choice for video work. But when using drives in a RAID, the rotational speed is not as important as the buffer size. The 7,200rpm drives that were being sold where I purchased the hardware, in the same price range, had very small buffers. The drives that I got have 2MB buffers, which are much more helpful in ensuring proper throughput.
 

This PCI card supports up to four Ultra ATA drives

The FastTrack appears to the computer and to Windows (95/98/NT/2000) as a SCSI controller. It has a built-in BIOS that enables you to quickly configure your drives as a RAID array and also lets your system boot up from them. The card offers all the usual RAID modes. For video work RAID 0, or striping, is what you want because it splits the load between both drives, effectively doubling their speed.

If you have never worked with RAID, it is important to mention that you need at least two drives for it to work. For maximum effectiveness, you should also obtain two identical drives. You can use drives with different capacities and speeds, but the smaller/slower one will dictate how the other is used. So, if you have one 40GB drive and one 30GB drive, you'll only be able to utilize 30GB on the larger drive, effectively losing 10GB of storage.

Because this particular controller supports two pairs of drives and because IDE drives come in much larger sizes than SCSI drives, you can have a lot of storage for the money. With 80GB ATA/66 drives going for as little as $250, you can put together a whopping 320GB RAID for less than $1,100 (including the RAID card). Compare that to a pair of not-so-fast (because of the smaller buffers) 7,200rpm 50GB SCSI drives at over $1,200 (without the controller)!

Okay, there's no arguing about the price. But what about the performance? After a very easy installation and set up on my NT workstation, I was ready to put it to the test. I had been using 10,000rpm UW/SCSI drives with a Targa 2000 RTX and AVID MC Xpress. I was able to get very high quality out of this setup, with visually lossless compression.

 

The two 30GB Ultra ATA/66 drives connected to the card via the supplied ribbon cables

When I used the Targa hard disk speed check utility with the RAID, I obtained lower results than I did with SCSI. That was a bit of a disappointment. But there's nothing like doing actual work on the system to measure true performance. And that's when I became pleasantly surprised.

I have never been able to utilize the SCSI drives at the fastest transfer rate suggested by the hard disk speed test utility. The problem is that while they could certainly work at that rate for a little bit, the drives would eventually fail to keep up and cause errors. As a result, I always worked at a considerably lower rate.

With the RAID card the opposite was true. I found that I could easily push it beyond the suggested rates without any problems. The nice thing about it is that its performance is entirely predictable. With my old SCSI setup, when a data "spike" would occur, the drives would not be able to handle it and the system would halt. The RAID, on the other hand, works flawlessly at the highest rate that I can squeeze out of it.

I guess that, due to the nature of striping, spikes are easily handled by both drives because each must handle only half the data spike. As a result, I can get the same final image quality out of the RAID as I can get out of the SCSI drives but with much increased reliability.

I am very glad I purchased the FastTrack. It gives me very high quality video, great storage capacity and improved reliability at a very reasonable cost. And Promise has a very good site (http://www.promise.com/), with constantly updated drivers and helpful setup information. I highly recommend the Ultra ATA RAID route to anyone in need of lots of fast, inexpensive storage.

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