An SCSI external hard drive is a hard drive that utilizes the Small Computer System Interface method of connecting to a computer. It is a connection standard similar to Advanced Technology Attachment (ATA) or Serial Advanced Technology Attachment (SATA). This method can also be used to connect other devices, such as optical drives, printers, tape drives, and scanners, to a computer.
SCSI, often pronounced "skuzzy," is a connection standard that was introduced to market in 1986, along with the ATA connection standard. Over the years, many improvements have been made, allowing it to become more widely used. Peripherals, such external hard drives, have been constructed to fit the standard.
In order to connect an SCSI external hard drive to a computer, an SCSI card must first be installed on the motherboard to serve as an adapter. Cards are available for PCI and PCI Express slots. Cables are also required to connect devices from the adapter card to the motherboard. There are several different cable options, depending on the peripheral device to be connected, so users should make sure they choose the correct one.
Though the cost of an SCSI external hard drive may be significantly higher than ATA or SATA, the reliability of the drive is much higher as well, making it worth the increased cost. While there is less storage space per dollar in cost compared to other connection standards, these drives are designed to run 24 hours a day, 7 days a week, for over 1 million hours without fail. SATA and ATA drives are designed to run only 8 hours per day, and often for much less than 1 million hours without fail. When estimating the cost of an SCSI peripheral upgrade, also consider the cost of the adapter card and cables, as these are traditionally not included. Without the card and cables, the device will not connect to the computer.
An SCSI external hard drive is not typically seen in the personal computing world, due to the cost and complexity of the connection. Businesses may want to consider using SCSI over SATA or ATA to protect customer data and equipment investments. For those who need great reliability in their computing, it is a viable solution that will pay for itself over time by reducing the chance of equipment failure and replacement.