5.3. Learning How SCSI Works

In the following sections, I discuss a type of device more popular than IDE drives in high-end machines, such as powerful workstations or servers — SCSI devices.

5.3.1. SCSI overview

SCSI is an acronym for Small Computer System Interface. The important part of this term is small computer, meaning that SCSI has its own brain — the SCSI adapter — that handles the SCSI environment. This SCSI adapter (also known as a SCSI card or SCSI controller) is responsible for managing all SCSI devices and controlling the conversation on the SCSI chain.

SCSI technology has many advantages over IDE technology, such as

  • The types of devices supported: SCSI supports a multitude of devices, including hard drives, CD-ROMs, scanners, printers, and tape drives, to name just a few. This is a huge benefit because originally IDE typically supported only hard drives and CD-ROMs.

  • The number of devices supported in a single SCSI chain (also known as a SCSI bus): Original versions of SCSI supported as many as eight devices in the chain, but one of those devices is the SCSI card added to the computer to give you the capability to use SCSI.


    IDE allows only two devices in the chain, and EIDE supports four devices. With SCSI, you are not only allowed to have more types of devices but also to have more of those devices!


    Original SCSI supports as many as eight devices in the chain. However, if the exam asks how many devices can be attached to a SCSI adapter, the answer is seven. ...

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