The SCSI Subsystem

Throughout this book, we’ve gradually traversed from the higher layers in the storage stack to the lower layer. We started from VFS, explored the major VFS structures and filesystems, and explored the structures and scheduling techniques in the block layer. The VFS and block layer represent a major portion of the software side of things in the I/O hierarchy. As we gradually move down the ladder and enter the physical layer, things are slightly more generic, as the lower-level standards used to address physical drives are the same for most systems.

The third part of this book contains two chapters that are dedicated to building an understanding of the physical side of things. In this chapter, we’ll mainly focus on one particular subsystem that has existed for a while and is the most common standard and protocol for addressing physical devices, Small Computer System Interface (SCSI).

The development of the SCSI protocol aimed to facilitate seamless...