Network Administration: Windows File Systems

Windows servers provide three choices for the file system format: FAT, FAT32, and NTFS. In most cases, you should choose NTFS. Well, actually, you should use NTFS in almost all cases. Come to think of it, you should always use NTFS.

The name FAT refers to the file allocation table, which was used in the original version of MS-DOS back when disco was still popular. FAT was a simple but effective way to track disk space allocated to files on diskettes and on small hard drives.

The original FAT system used 16-bit disk addresses to divide the total space on a disk into 65,526 units, called clusters, each of which could be allocated to any file on the disk. The size of each cluster could vary from as little as 2K to as much as 256K, depending on the size of the drive.

When disk drives started to get bigger than 512MB (can you remember when 512MB was a huge disk?), FAT was upgraded to FAT32, which used 32-bit addresses for clusters. That allowed a maximum of 524,208 clusters on the disk with the size of each cluster ranging from 4K to 32K, depending on the size of the drive.

FAT32 was a nice improvement over FAT, but both suffer from several inherent problems:

  • Even with 32-bit addresses, FAT32 is stretched by today’s 200GB+ disk drives.

  • Neither FAT nor FAT32 has built-in security features.

  • Frankly, FAT and FAT32 are inherently unreliable. Most users, at one time or another, lose files due to the unreliability of FAT/FAT32.

  • FAT and FAT32 allocate space inefficiently on large volumes because the smallest unit of space that they can allocate must be large — as much as 256K in some cases.

Here are just a few of the reasons why choosing NTFS for Windows servers is a no-brainer:

  • NTFS has built-in security features that track security information for individual files and directories.

  • NTFS tracks clusters with 64-bit disk addresses rather than 32-bit addresses (FAT32) or 16-bit addresses (FAT). As a result, an NTFS volume can theoretically have something in the neighborhood of 18 million billion disk clusters, which should keep you going for awhile.

  • The benefit of having so many clusters available is that the size of each cluster can be kept small. NTFS can efficiently use 4KB clusters for even the largest drives available today.

  • NTFS drives are more reliable because NTFS keeps duplicate copies of important information, such as the location of each file on the hard drive. If a problem develops on an NTFS drive, Windows can usually correct the problem automatically without losing any data. In contrast, FAT drives are prone to losing data.

  • The system that FAT uses to keep track of which disk clusters belong to a given file is prone to errors. In contrast, NTFS has more redundancy built into its record keeping, so it’s less likely to scramble your files.

  • NTFS has better support for large drives and large files. The following table compares some of the upper limits of the FAT, FAT32, and NTFS file systems.

File System Limits
Maximum volume size 4GB 32GB 16TB
Maximum file size 2GB 4GB 16TB
Maximum files per folder 512 65,534 4,294,967,295
Maximum files per volume 65,526 524,208 Too many to count