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6/96 Features: Trickle-Down Technology

High-end SCSI technology is making its way onto adapters geared toward mainstream users

By Serdar Yegulalp, Technical Editor

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SCSI Hardware

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68-Pin Ultra SCSI

Until recently, choosing a SCSI adapter meant deciding between price and performance. But now there's a middle ground. Technical innovations that were previously the forte of server- and workstation-oriented users are making their way onto lower-priced products geared more toward the average PC user. At the same time, the more specialized cards are becoming easier to install and use.

The most common complaints about SCSI controllers concern configuration issues, but this is changing as PCI becomes the bus of choice among hard-core SCSI users. PCI's Plug-and-Play features consign to oblivion the ritual mumbo jumbo of jumpers and DIP-switch settings.

For options that users do want to manage-like memory locations, low-level drive formatting and boot choices-any SCSI card worth its salt now has all its configuration controls in ROM, usually accessible with a special key at boot. Flash upgrades for SCSI adapters' on-board ROM chips are standard as well, so you need little more than a floppy disk to upgrade.

Simple and convenient innovations are becoming ubiquitous. Smart termination, for instance, is a standard feature on just about any SCSI adapter sold today, whatever its price. Here's how smart termination works: Devices at either end of a SCSI chain have to be terminated. This is done by outfitting them with resistors to ensure electrical signal quality. The adapter itself may also need to be terminated, which traditionally required you to change settings on the board. But now manufacturers are adding the hardware and on-board code needed to make an adapter auto-terminate, saving you from going through the tedious process.

Absolute Power

Power management is a slightly more complicated proposition. Most current host adapters are designed to work under the Energy Star standard, powering down each component when not in use. For example, a SCSI scanner with power management saves both energy and the life of its lamp over the long haul. However, as with many other newer SCSI features, power management can be fully used only if all the devices on the chain are similarly compliant. All the more recent SCSI devices have the necessary environmental savvy, but SCSI hardware more than a year old won't support this sort of power management.

What a SCAM!

Some of the newer features have an almost James Bond-like sophistication. SCAM (SCSI Configured Auto-Magically), for example, is a new standard that automatically assigns ID numbers to SCSI devices at power-on. This is a convenient addition for those who often hot-swap drives, reconfigure on the fly or just have no inclination to set the numbered dials behind their SCSI peripherals. It also eliminates the burden of prioritizing SCSI devices, which means you no longer have to decide if you should access the CD-ROM drive before or after the scanner.

Many of the newest adapter cards, including BusLogic's BT-958, support both 8- and 16-bit connectivity on the same card, simplifying the upgrade process. Distributed Processing Technology's SmartCache IV card offers the same connectivity, plus another feature you may be seeing more often: upgradability via subboards. SCSI is the disk controller of choice for those seeking blow-the-doors-off performance, and DPT's cards allow you to add up to 64MB of cache RAM and RAID capability in this manner. Those who want to start with a baby server and grow it into a granddaddy later will appreciate the ability to add power as needed.

The dual-channel adapter is another interesting new wrinkle. Cards like the BusLogic FlashPoint DL, which packs two 8-bit narrow SCSI-2 channels onto one board, do more than just provide connections to up to 14 SCSI devices. These cards have two discrete channels, so you can allocate one for slower devices like CD-ROM drives, scanners, magneto-optical drives or tape backup systems, while keeping a second for hard drives only. On a system with a SCSI hard drive that takes hits regularly, that much extra bandwidth makes a difference.

Chain of Tools

Because they were often used as drive controllers, higher-end SCSI cards allow hard drives on the SCSI bus to be used as boot devices. At first, the device range was limited strictly to standard hard drives-and then only to the first drive on the chain, with a certain ID number. Now, with most boot-BIOS SCSI cards, any hard drive on the chain can serve as the boot device. In some cases, you can also boot from a CD-ROM drive. A bootable CD-ROM simplifies the configuration and deployment of operating systems: Insert the disc, fire up the computer and sit back. Previously restricted to higher-end server systems, this feature is beginning to appear on some mass-market IDE controllers that support ATAPI CD-ROM drives.

Despite the trickling down of the hottest SCSI technologies, some innovations are still beyond the average user's grasp. The 68-pin Wide Ultra SCSI-2 and SCSI-3 configurations in higher-end cards are wasted if you use low-bandwidth devices. Scanners, for example, need only an 8-bit connector and are often packaged with inexpensive 8-bit cards. Also, many higher-end storage devices are astronomically expensive by most consumer-price standards. But this, too, is changing. As little as 18 months ago, a 1GB single-cartridge storage system (like Iomega's Jaz drive) didn't exist. Now it looks like the first real floppy-killer to come down the pike.

Trends like these in SCSI technology could prove that the trickle-down theory works after all.

Where to Get SCSI

Host adapters
800-959-7274, 408-945-8600

Host adapters
800-525-7443, 408-383-9400

RAID controllers, host adapters
408-492-9090, fax 408-492-1542

IQ Technologies
PCMCIA SCSI adapters
800-227-2817, 206-823-2273

Host adapters
800-LINK-SYS, 714-261-1288

Mylex Corp.
RAID controllers
800-77-MYLEX, 510-796-6100

QLogic Corp.
Host adapters
800-TOP-SCSI, 714-668-5037
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