Tom's Hardware Guide is known as the premier source for computer hardware information. Running several hardware labs and proudly serving one of the largest readerships worldwide, we are ready to expand our activities to the storage sector as well. For me it is an honor to be the editor who does the first hard disc drive review, as this is meant to introduce a series of periodical articles. This initial one deals with six hard drives from Fujitsu, Quantum, Seagate and Western Digital. I'm sorry that we did not include drives from Maxtor and IBM, but I promise that we will include their products for the next articles.
IDE Vs. SCSI
Of course there was the question of whether to start with an IDE or a SCSI hard drive review. SCSI is still the most flexible and of the two, it is the faster bus system. Ultra2Wide-SCSI is the common standard, allowing up to 15 drives in the SCSI chain and enabling a bandwidth of up to 80 MByte/s. High performance drives are available with an Ultra160 interface, which gives you double the bandwidth. But those terrific speeds are highly priced. SCSI drives are at least a third more expensive than IDE models. Furthermore, you will need an SCSI host adapter. IDE interfaces can be found on every motherboard for the past few years now, whilst only a minority of all motherboards is being produced with an on-board SCSI chip. If you want to spend all that money, you will get a very solid base. Regarding the pure data transfer rate, there is no difference between two identical IDE and SCSI drives. SCSI systems can be faster if you use several drives in a RAID configuration. That is also possible with IDE, but currently still restricted to the maximum IDE bandwidth of 66 (ATA66-spec) and very soon 100 MBytes/s (ATA100-spec). Some drives can also be faster thanks to the special SCSI features (command queuing) or just by being the latest generation high end drives. As high end computers usually require best performance, the fastest drives are primarily developed for the SCSI interface.
IDE, on the other hand, is much easier to handle. As only two drives can be attached to an IDE port, there is only the Master or the Slave setting. No drive ID is required and the bus does not require any termination. Incompatibilities between two drives have become very unusual in the last years. Moreover, I'd guess that most of our readers make use of IDE drives, which is apparent hundreds of emails asking for advice.
IDE Vs. SCSI, Continued
As already mentioned, it is also possible to run IDE RAID systems at very low cost, as IDE RAID controllers are very cheap compared to SCSI models - but they are usually limited to four drives. Moreover, you can use cheap IDE drives. When using two drives, the data transfer performance will practically double, and you will get even more performance using three or even four drives. Anyhow, you should know that performance does not increase linearly. Two drives still double your performance, whilst three drives do not provide triple the transfer speed any more. Using four drives will reach the limit of UltraDMA/66 at the most, so that you will usually get approximately 3.5x performance.
This photo shows the 40 pin IDE connector. Please note that a UDMA/66 cable comes with 80 pins, while the connector only has half the pin count.
That's how the older SCSI connectors look like (SCSI, SCSI-2 or FastSCSI, UltraSCSI).
The latest SCSI devices make use of the Ultra2Wide interface, but normal Wide and UltraWide SCSI (20 and 40 MByte/s) make use of the same 68 pin connector.
This one is the 34 pin FDD connector!