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Serial ATA vs. SCSI - Will it Compete?
fazzumar asks: "I've been checking out serial ATA (SATA) and it seems like it's got a lot of potential. The first generation spec was finalized August 2001 and members of the SATA group anticipate a 12-18 month acceptance period. They've planned for a cut-over phase and adapters that allow connecting SATA devices to ATA adapters and vice versa. The cables alone are a worthwhile advantage (4 pins, up to 1 meter in length), and the 150MB/sec bandwidth is a (minor) improvement over current ATA drives & adapters. Infoworld has a story on SATA that provides a few tidbits of information. What I really want to know is, will manufacturers of the new host adapters be able to integrate many of the advantages that SCSI provides or will the cost of adding these features push the retail cost too high for the anticipated market?" I just picked up a new WD Hard drive just yesterday for the planned MP3 jukebox I hope to be building near the end of the summer. I really wanted to go SCSI, but couldn't. While the poster claims a near ~7x in price difference, I saw about a ~5x difference in my local store. Is SCSI in danger of falling behind IDE drives (especially serial IDE drives) in popularity?
"I love SCSI, and I can bring myself to accept the additional cost of the controller, but with IDE hard drive prices dropping, I frequently wonder if SCSI drive prices are artificially inflated. Just a few years ago, SCSI drives were ~10-20% more than IDE and now they're ~7X more than an IDE drive. (Seagate 10k RPM SCSI - ~18 gig for ~175. Western Digital 7200 RPM IDE - ~120 gig for ~175) If the option comes out to get SCSI performance from an IDE drive I'm going to take it."
The major difference is Queuing and Parallel Processing. Even today's IDE RAID controllers can't get more than one instruction down the pipe at the same time, and queuing is non-existent. Recently I have seen IDE cards that support extra RAM, but specs on the boxes don't read like they support queues. SATA will introduce the concept of a queue, and that will speed I/O greatly, but the biggest speed barrier is the speed at which the instructions are sent to the disk.
I run a small video editing shop. Real time video editing taxes disk I/O on PC's more than anything else I know of. I HAVE to run SCSI, and still, even with SCSI, I have to wait. Most of the time I am waiting on the I/O.
That being said, after reading the SATA standards, I will feel safe replacing more than half of my high-speed I/O channels with it. I am willing to have it manage everything except the most extensive reads and writes. I will soon be dedicating a portion of my web site to the explanation of SCSI vs. SATA. Bookmark it now.