The FAT and FAT32 file systems

Tuesday, 6 May 2008

The FAT file system divides space on a fixed disk into exactly 65,536 (16 bits’ worth, or 216) storage locations, and each location is assigned a number. The storage locations are also known as clusters.A cluster is the smallest unit of storage space on a FAT partition.

File location in these storage spaces is tracked by the File Allocation Table, which, as mentioned earlier, works very much like the table of contents for this book it’s simply a way of keeping track of the reality that in cluster (page number) x lives file (topic) y.

FAT32, then, is an updated version of FAT that generally uses smaller cluster sizes, simply because it creates so many more of them (232 of them, to be exact). Smaller cluster sizes generally result in more efficient use of a logical drive’s disk space and, moreover, support much larger drives.

But neither version of FAT is the default file systemused byWindows Vista at setup time. NTFS is the default, and this file system makes even better use of larger drives.Moreover, the NTFS file systemmakes available a host of improved security features over FAT.

So, why on earth would you want to format a drive using the FAT32 file system? In a word: compatibility. The FAT32 file system was first introduced with the release of Windows 95 OEM Service Release 2 (OSR2), and it has been supported on allWindows versions since then. If your goal is to store data on a drive thatwill be used on earlierWindows versions, FAT32 might be your best choice. However, it is not compatible with Windows NT versions 4.0 and earlier.

The NTFS File System

NTFS (or NT File System, depending on who you ask) was first used with the Windows NT operating system many years ago and has been steadily improved ever since. It provides the highest level of performance and features for Windows Vista computers and, thus, is the default file system used at installation. In fact, many of the enhancements to Windows operating systems over the years (especially in terms of security) are technically enhancements to the file system, which continues to evolve much like any other software component. And, as mentioned earlier, the big leap forward that Vista originally promised was indeed an overhaul of the file system used.

At the time of this writing,Vista uses NTFS version 3.1. The file systemtechnologies included with NTFS 3.1 include compression, quotas, and encryption technologies that haven’t always been a part of the Windows NTFS environment. All of these technologies get coverage within this book. NTFS supports volumes of up to 2 terabytes, and as with FAT32, cluster size is relatively small. This means NTFS makes efficient use of disk space and is well suited for larger drives.

Another significant advantage of NTFS is that it allows for local security of files and folders, which is especially important when two or more users are accessing the same computer.With NTFS, different users can be assigned different levels of access to a resource. For example, one user may have access permission to change a particular file,whereas another user has permission to only read that file.

This kind of local security is not possible with a FAT partition. The biggest drawback when using an NTFS volume is compatibility, although this is becoming less of an issue as time goes on.Windows 9.x computers don’t have the necessary file system drivers to read data from NTFS partitions. Windows 2000, XP, and Server 2003 operating systems do. About the only instance in which you would need to format your Vista systemdrive with the FAT file system today is if you plan to dual-boot with Windows 98.

This issue of file system choice is sometimes confused by the fact that a Windows 9.x computer can still access data housed on an NTFS partition as long as that access occurs over the network. In that case, the Vista computer fields the request from the Windows 9.x system and then retrieves the appropriate file system drivers needed to access the data. In practice, that means you can have a work group set up with some computers running Windows 9.x and some running Vista without having to worry about formatting all your Vista drives with FAT. If you’re already certified or have experience on Windows 2000 or Windows XP, you probably found much of the preceding discussion to be a review. And indeed it is: not much has changed in Windows Vista as far as file systems go. You might see a question or two about it on the 70-620 exam, however, because these choices do affect post-installation capabilities.

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