how laser printers work
ip assignment
scsi vs ide
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index -4 short answer questions 1 essay


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SCSI vs ATA (IDE)
To make a fair comparrison between modern SCSI (SCSI-3) and ATA (ATA/ATAPI-6) you have to look at two different scenarios: Single device and multiple device environments. 

Single device 
This scenario is common in desktop computers where you connect a single device to a single adapter and perform data transfers. There is practically no difference between the two interfaces, this holds for bandwidth as well as resource usage (CPU) as both interfaces use the most efficient way to transfer data, namely DMA. This means that there is no point in purchasing a generally speaking more expensive SCSI based system when the cheaper ATA interface would do an equally good job. 

Multi device 
This scenario is common in high-end desktop computers and servers where you connect multiple devices to one or more interface adapters. This is where SCSI has major advantages compared to ATA: 

Connectivity: The ATA interface can only address two devices while SCSI can address eight devices (Narrow SCSI), 16 devices (Wide SCSI), 32 (Very Wide SCSI) or 126 (FireWire). There are also many peripherals available to SCSI only and not ATA. 
Bandwidth: The demand for high transfer rates in servers can not be met using current ATA interfaces based on the two devices per adapter limit and even if it could carry more devices there simply isn't enough bandwidth and flexibility available for serious server application. 
Efficiency: The ATA devices lack the intelligence to perform command queuing as well as their SCSI counterparts which can queue up to 256 commands per logical unit. SCSI hard disk drives aimed at the extreme performance server market have had a lot of research and development time on optimizing seek patterns and rescheduling commands to minimize seek times and maximize throughput. This may not be evident by looking at desktop benchmarks but under heavy server loads, this is evident.
Also, SCSI hard disk drives generally tend to be designed to work well in RAID-systems where I/O load is spread across multiple drives. 
Dependability: Most high-end SCSI hard drives are quite expensive but there are good reasons for it. They can sustain higher temperatures and stay mechanically functional despite the expansion of the metal parts with temperature and and generelly have better build quality. The net result is that they are the natural choice for enterprise server applications. Connectors suitable for hot-swapping drives in RAID-systems is something only SCSI boasts, and helps maintaining large disk arrays where down-time is unacceptable.