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!