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HBA Devices and I/O Processing

A host bus adapter (HBA) is a device that provides a connection between a set of peripheral storage devices and a computer or between nodes on a network. In addition, an HBA device may provide some I/O processing—such as segmentation and reassembly, flow control, error detection, and interrupt handling—that improves I/O throughput.

This chapter describes how HBA devices are represented and managed in Mac OS X and it introduces the SCSI Parallel family, which provides support for HBA drivers. This chapter also describes the path of an I/O request and how an HBA device driver participates in that journey.

If you need to develop a custom driver for an HBA device, you should read this chapter to learn how your driver fits into the system and how to take advantage of the services provided by the SCSI Parallel family. When you're ready to begin development, read “Developing an HBA Driver” for specific guidelines on how to implement your driver and “Improving Performance” for ways to improve its performance.

Contents:

HBA Device Drivers in Mac OS X
The Role of an HBA Device in the Journey of an I/O Request

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