Most common Windows file systems

Along the way the company has also been upgrading its file systems to add additional features, reliability and security needed for corporate users. In this article we look at the various types of file systems now supported by Windows.

Windows Disk Systems supports two file systems for magnetic disks – FAT and NTFS. NTFS (short for NT File System) is the preferred system for Windows NT 4.0, 2000, XP, Vista, Windows 7 and .NET server and workstation operating systems, but these O/Ses still support the older FAT (File Allocation Table) file system for use with floppy disks and with older versions of Windows in multi boot systems. To take full advantage of the security, disk quota and other features of the later software, however, you will need to be using NTFS.

FAT
FAT started being used with DOS and there are now three different versions of the File Allocation Table file system - FAT12, FAT16 and FAT 32. The numbers used in these versions designate the number of bits used to identify a cluster.

FAT12:
The earliest version the file system, FAT12 allows a partition to contain up to 4096 (212) clusters. Since it supports clusters of one to sixteen sectors, the maximum partition size is 32MB. Windows 2000 uses FAT12 for floppy disks and for partitions of 16MB or smaller.

FAT16:
FAT16 provides a sixteen-fold expansion in the number of clusters it identifies, supporting volumes containing 65,536 (216) clusters. It also expands the maximum cluster size to 128 sectors (64KB) and maximum volume size to 4GB.

FAT32:
To address the need for even larger storage capacity, Microsoft introduced FAT32 with Windows 95 OSR2. Following the pattern of the earlier versions of the file system, it uses 32 bits to designate a cluster. However the last four bits are reserved. Each volume, therefore, can contain up to nearly 270 million (228) clusters which theoretically translates into a 8 Terabyte volume comprised of 32KB clusters. In practice, however, while Windows 2000 will manage larger volumes created in other operating systems, it limits the size of new FAT32 volumes to 32GB since the file system becomes quite inefficient beyond that size. If you do want to create a larger volume, you can dual boot the system into either Windows 95 or 98, establish the volume using that OS, and then manage the volume using Windows 2000.


NTFS
While each of the FAT versions represents an incremental improvement over its predecessor, NTFS takes a completely different approach to the way that data is organized. It grew out of Microsoft's desire to increase its share of the corporate marketplace. FAT was a very simple system which worked for PCs, but it lacked the management and security features needed to compete with UNIX in a high-end, networked environment. The first attempt at a newer file system was the High Performance File System (HPFS) introduced with OS/2 Version 1.2. When the IBM/Microsoft partnership that created OS/2 fell apart, and Microsoft decided to create Windows NT, it incorporated some of the features of HPFS into its New Technology File System (NTFS).

NTFS is the native file system for Windows NT 4.0, 2000 and XP operating systems. While these O/Ses can operate with FAT, many of their features only work with NTFS, so NTFS should be used whenever possible. Fortunately, if you have one or more FAT partitions running on one of these operating systems, it is a simple matter to convert them to NTFS without losing any data.

NTFS, a log-based file system, addresses FAT's reliability and recoverability problems. A partition's clusters are numbered sequentially using a 64-bit logical cluster number (LCN). Theoretically this system would allow access to 16 exabytes (16 billion GB) which far exceeds current storage needs. For now, Windows 2000 limits volumes to 128 Terabytes, but later operating systems could take advantage of even larger storage capacities. Like FAT, it sets a default cluster size depending on the size of the partition, assigning a size of 4KB for anything over 2GB. Also like FAT, administrators can override the defaults and use drop-down box to specify sizes up to 64KB.

Article Source: http://www.auerbach-publications.com/dynamic_data/2770_1640_Windows%20File%20Systems.htm


Related Articles:
You can convert file system from FAT to NTFS without data loss by using Partition Assistant.