CompTIA A+® Certification All-In-One For Dummies®, 2nd Edition

5.6. Understanding File Systems

The file system dictates how information is organized on the disk. For example, the file system determines how large the allocation unit, or storage unit, of a file is. If you create a 12K file, how much space is that file really using — 12K, 16K, or 32K? Such organizational issues are what the file system deals with.

The following sections introduce the different file systems available and the OSes that support them. You also find out what features the file systems do and do not support.

5.6.1. The FAT file system

The File Allocation Table (FAT) file system has been the most popular file system up until the last few years. Although the FAT file system is the most common (it can be used by all OSes), it is losing the popularity contest to its successor — FAT32 — because of its age and limitations.

The FAT file system was the file system used by DOS, Windows 3.1, and Windows 9x; and is supported in all current versions of Windows including Windows Vista. FAT's biggest strength is that it is the file system most widely understood by different OSes — but it has many shortcomings. One of the major shortcomings is that it cannot create a partition larger than 2GB. (A discussion of partitions is coming up in the "Managing Partitions and Volumes" section; for now, consider a partition simply as a discrete portion of space on the disk.) The 2GB size limit was not a major limitation until hard drive sizes exceeded a few gigabytes. For example, a problem ...