Tip: Turn external drives on before you boot your computer.
Most computer owners figure that they can turn on their computers and external toys in any order, but that approach can cause problems -- especially with external SCSI drives, which are particularly sensitive to these matters. As a rule, turn on all external peripherals first, like your printer, scanner, and CD or DVD recorder.
You can easily take care of this problem once and for all: Buy a surge suppressor or UPS (uninterruptible power supply) for your system and plug your computer and all your peripherals into it. Just leave everything plugged in and switched on. Then use the switch on the surge suppressor or UPS to turn everything on at one time. (Think of it as that big master switch that Dr. Frankenstein always pulled to start everything in the laboratory.) Because your external stuff comes on instantly (before your computer even gets started booting up), this method is the same as turning on everything external by hand.