RADIFIED
Guide to Booting from a SCSI Drive

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Major Premise

The disk storage subsystem is - by many orders of magnitude - slower than both your CPU & RAM. CPU clockrates have already bust thru the 3GHz barrier (tho my system currently runs at a paltry 2.13 GHz).

RAM is so fast that adding any is virtually guaranteed to increase your system's performance (if you can put it to use). With CPUs & RAM, we're talking about performance in terms of nanoseconds - or, 1 billionth of a second.

People tend to be more familiar with billion than nano, but billion (Giga) and nano are similar in magnitude - in opposite directions. Whereas billion is big/long, nano is small/short. But both have 9 zeros, on different sides of the decimal point.

By contrast, when we talk about hard drive performance, we're talking in terms of milliseconds (small m - three zeros). You don't need a degree in Mathematics to see that the difference is huge. The difference between nano (CPUs & RAM), and milli (hard drives) is .. Mega (big M).

In other words, today's hard drives are (literally) a million times slower than your CPU & RAM. Put in monetary terms (which everybody understands), milli (3 zeros) gives you $1,000 - while billion (9 zeros) gives you $1,000,000,000. See what I mean?

In the High-End Buyer's Guide, Mike Andrews of Anandtech echoes these sentiments here, by saying:

Hard drive performance has always been one of the biggest bottlenecks in the speed of a computer. After all, the only component whose speed is measured in milliseconds is the hard drive – everything else is nanoseconds or microseconds.

Even with the fastest drive on earth right now running at 15,000 RPM, the Seagate Cheetah X15 still has an access time of "only" 3.9 ms. Now 3.9 ms is phenomenal for a hard drive, but still an eon compared to 133 MHz SDRAM.

Now you don't always use your hard drive, but you use it a lot. Some folks use theirs more than others. It depends on what kinds of things you do with your PC. In each case, it depends on the individual user. But the way in which Windows is designed, everyone uses their hard drive much more than their CD-ROM, which is much slower (~10X) than the hard drive.

And this is one of the major factors which determines whether SCSI is right for you. The more you use your system in ways that access the hard disk (read from or write to ), the more benefit you will derive from a SCSI boot drive.
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Using a concept known as of the limiting factor, we can see that a family can only walk as fast as its slowest member - be it one of the kids or granny. In like fashion, anything we can do to increase the performance of our slowest frequently-used system component (hard drive) has the likelihood of producing a significant effect on our overall system performance.

"If this is true," you might be asking yourself, "why doesn't everybody boot their system from a SCSI hard drive?" Good question. Two reasons:

  1. First, like the <qualifier> suggests, not everyone uses their PC in ways that take advantage of the benefits offered by SCSI hard drives and the SCSI interface. These are folks like my grandma, who only uses her PC for email, occasional word-processing (to make her shopping list for the grocery store), & surfing the 'Net .. to find the latest bingo scores.

    But if you do things like video editing, audio recording & editing, image or graphics editing, heavy multitasking, you're not in the same category with Gram. And I have a hunch that, if you found your way to Radified, you're someone who will appreciate the performance that SCSI offers, and will put it to good use. This leaves only item #2 below as the sole determining reason for determining whether SCSI is right for you.

  2. Cost. SCSI costs more than IDE. Not only do SCSI drives themselves cost more than IDE drives, but you'll also have to purchase a SCSI adapter card, or a motherboard with a onboard SCSI controller.

    You see, IDE/ATA drives are designed primarily with value in mind (not performance). You get much more space with an IDE/ATA drive. SCSI drives, on the other hand, are designed primarily with performance and reliability in mind (not value).

    All motherboards currently come with (at least) two IDE/ATA controllers onboard. If you want to use SCSI components in your system, you'll have to pay extra for a controller - either integrated onboard, or with a separate PCI card. (I recommend the later approach.)

You can trade in that clunker and drive out of the showroom in a shiny new SCSI-based rocket for somewhere in the neighborhood of US$250. This includes the cost of both an 36GB enterprise-class (10Krpm, new) hard drive and an Ultra160 SCSI adapter card (also new).

This calculation is based on using the LSI Logic Ultra160 SCSI adapter card (~$59) and an 36GB Maxtor Atlas 10K IV (~$189). It wasn't that long ago when this number was twice as big. Personally, I use the Tekram DC-390U3W SCSI adapter, because I have a SCSI CD-ROM and burner.

I like the Atlas 10K IV. It is the best-performing 10Krpm drive that you can buy right now. I own an Atlas 10K III and like it. I also own a Seagate Cheetah x15-36LP that I like even more.

Fastest Drive on the Planet

The current reigning FDOP (fastest-drive-on-the-planet) is the Cheetah 15K.3, manufactured by Seagate, the acknowledged leader in high-end SCSI drives. Seagate produced the first 10Krpm spindle, and the first 15Krpm spindle. The X15-36LP is available in 18GB, 36GB and 73GB sizes.

Note that a 15Krpm spindle is over twice as fast as the fastest IDE/ATA drives currently available on the market (7200rpm). For those who absolutely, positively gotta have the fastest drive that the universe has to offer, the 15K.3 sells for about US$209 [18GB], and US$320 for the 36-gigger.

Wow, they've really come down in price since I last checked .. now in my price range. Only $70 more than the Atlas 10K III. Dang, I might have to get me one of those bad boys.

If you wanna see what kind of performance your money buys you, I posted an HD Tach benchmark of the Seagate Cheetah X15-36LP hard drive, and also an Atto benchmark of the Seagate Cheetah X15-36LP, both compliments of skypx (thx, hombre).

Note that the Cheetah X15 (not the 36LP flavor) is the first-generation 15Krpm SCSI drive from Seagate. The second-generation X15-36LP is better/faster. The 15K.3 is their 3rd-generation drive and faster still.

Before buying any hardware online, you should always (always!) check with a price-comparing service such as Pricewatch & Shopper, and a vendor-evaluator like Resellerratings .. to verify that your prospective reseller is both established and reliable. New Egg is also a good place to shop. I've purchased drives thru Hypermicro, and found them to be reliable & competitively priced (no California tax).

Purchase only from established vendors with a good track record. Use a minimum Reseller rating of 5.5 as a good rule of thumb. Don't buy anything from a vendor with a rating of less than 5.0. I've deviated from this practice only twice. Both times I was in a hurry, and wound up sorry that I hadn't spent a few minutes checking. =(

At this point, the obvious question in everyone's mind should be: Is SCSI worth it for me?
The obvious answer is: it depends ... and this is what it depends on: