SCSI Interface

Does My System Need SCSI???

As we have seen the performance of CPUs increase over the last year or so, we begin to notice that the possibility of I/O bottlenecks become more and more a reality. Faster system buses, larger, faster caches, increased memory bandwidths, and AGP graphics adapters with greater and greater onboard framebuffers ease the situation somewhat, but if you really want to future-proof your existing super7 system, it may be time to take a look at SCSI (Small Computer System Interface).

SCSI is an !/O bus for connecting peripherals to your computer via a standard hardware interface, which uses standard SCSI commands. This standard can be divided into SCSI (SCSI1) and SCSI2 (SCSI wide and SCSI wide and fast). The newest incarnation of SCSI, known as Ultra2 SCSI, offers twice the bandwidth of the current UltraSCSI (Fast-20) standard, up to 80MB/s, to address the need for greater I/O throughput. ( Note : While there currently isn't a harddrive available that can push data at anywhere near that speed, the use of multiple drives, properly managed, can make great use of such high speed connectivity. )  In addition to providing much higher bandwidth, Ultra2 SCSI increases the maximum allowable cable length, once a somewhat limiting factor, to improve connectivity and flexibility. Wide Ultra2 SCSI can support up to 15 devices on 12 meters of cabling.  Ultra2 SCSI offers possibly the best support for multitasking and multithreaded I/O, a fact that has made it synonamous with performance-driven systems. Ultra2 SCSI also finds support with most major SCSI adapter and drive vendors.

As our systems become more capable, new applications evolve to take advantage of the increased available features and performance. Video editing, for example, is rapidly moving from specialized, high-end systems to SOHO desktops and workstations. Real time video applications can require more than 30MB/s of sustained data throughput. Other applications can also require huge amounts of I/O bandwidth includind 3D modeling and simulation, and data mining.

Keeping up with the power and performance of todays CPUs requires the development of larger, faster hard disk protocols. Hard disk drive data rates, however, tend to improve a bit more slowly than drive capacity. And, although drives keep getting bigger and faster, applications seem to stand in line just waiting to take full advantage.

While the SCSI interface may have been created well over a dozen years ago, it still has a bright future because it continues to adapt to the ever-advancing technological environment. SCSI still maintains backward compatibility with legacy devices, so users will always find support for the broad and growing array of SCSI compliant peripherals such as scanners, CD-ROMs, and tape drives, as well as a viable upgrade path for future peripherals.

But doesn't USB have the same advantages?

Well not really. USB is a relatively new interface that is designed to connect miscellaneous low speed peripherals external to a PC. It operates at 12 Mbits/s (or about 1.5MB/s). It can handle things like keyboards, mice, modems, digital cameras, scanners and some printers etc. It is not, however, intended for storage devices and is in no way a replacement for IDE or SCSI. 

If you are content just playing a few games and surfing the web, then by no means do you need to spend the extra money for a SCSI host adapter or the more expensive hard disk drives to connect to it.  On the other hand, if you are interested in keeping a top of the line performance based system, follow along as, over the next few weeks, we reveal in depth the process of installing a new SCSI host adapter and high performance SCSI HDDs as well as a few other SCSI based peripherals.

Adaptec 2940U2W SCSI Host Adapter Kit Review

Last Updated Jan. 2, 1999

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