Windows 2000 Performance Guide

Filesystems

Once a disk has been placed under the control of the operating system as either a basic or a dynamic disk, the next step is to create a filesystem structure on top of it. A filesystem consists of algorithms and data structures that manage the storage of files and directories on the disk, keep track of disk blocks that are available and disk blocks that have already been allocated to files. Some filesystems provide advanced features such as access control, disk quotas, and encryption. Different filesystems make different choices as to the data structures and algorithms that they use to perform their responsibilities so they exhibit different performance characteristics.

Windows 2000 provides three choices in selecting a filesystem: the FAT16, the FAT32, and the NTFS filesystem. The FAT16 and FAT32 filesystems are very similar in organization. Windows NT 4.0 provided two choices for a filesystem, as the FAT32 was introduced in Windows 2000 although it has been in the Windows 9x line of operating systems for a while. In this section, we describe the organization of these three filesystems from the performance point of view and indicate the advantages and disadvantages of each one.

The FAT Filesystem

The FAT (or FAT16) filesystem is a simple filesystem that has its origins in the good old days of the DOS operating system. When a disk partition is formatted using the FAT filesystem, the available space is divided into equally sized units called clusters. The size of the ...