Chapter14.File System Fundamentals

Chapter 14. File System Fundamentals

Upon completing this chapter, you will be able to

• Understand the fundamental role file systems play in storage I/O processes

• Explain the differences between file systems and operating systems in storage I/O processes

• Describe the structural elements of file systems, including the directory system and layout reference system for locating data

• Identify different file systems' components and features

This final part of the book discusses the different forms of filing software. In general, filing is responsible for placing and locating data within storage address spaces. The most common types of filing products are file systems and databases, but certain data management applications like backup and Information Life Cycle Management are also applications of filing.

If you analyze storage as a hierarchy or stack of functions, filing is always the topmost level inside a system initiating an I/O request. The relationship between systems and storage is not necessarily symmetrical because SAN storage, or block storage, does not provide any filing functions. NAS storage, however, by definition, does. NAS is discussed in the following chapter.

Regardless of whether SAN or NAS storage products are used, filing functions are seminal to all storage processes as the starting point for I/O operations. While it is true that applications read, create, and update data, filing systems initiate the storage I/O process in the system on behalf of the application that requests services from it.

This chapter introduces the fundamentals of file systems and is the basis for more advanced topics in the chapters that follow.