Friday, May 24, 2013

What is FAT and NTFS ?


FAT Definition:

FAT, short for File Allocation Table (used by hard disks, disks, Smartmedia™, Compact Flash™, Memory Stick and other), 
A table that the operating system uses to locate files on a disk. Due to fragmentation, a file may be divided into many sections that are scattered around the disk. The FAT keeps track of all these pieces. 
It is a file system that was created by Microsoft in 1977. FAT ( also know as FAT, FAT16, and FAT32 ) is still in use today as the preferred file system for floppy drive media and portable, high capacity storage devices like flash drives.

FAT was the primary file system used in all of Microsoft's consumer operating systems from MS-DOS to Windows ME. The New Technology File System (NTFS) is the primary file system on Microsoft's newer operating systems but FAT is still a supported option.

Below is more information on the versions of the FAT file system:
  • FAT12 - The initial version of the FAT file system, FAT12 was introduced in 1977, even before MS-DOS, and was the primary file system for Microsoft operating systems up to MS-DOS 4.0. FAT12 supports drive sizes up to 32MB.
  • FAT16 - The second implementation of FAT was FAT16, introduced in 1981. FAT16 was the primary file system for MS-DOS 4.0 up to Windows 95. FAT16 supports drive sizes up to 2GB. It was designed originally to handle files on a floppy drive, and has had minor modifications over the years so it can handle hard disks, and even file names longer than the original limitation of 8.3 characters, but it's still the lowest common denominator. The biggest advantage of FAT16 is that it is compatible across a wide variety of operating systems, including Windows 95/98/Me, OS/2, Linux, and some versions of UNIX. The biggest problem of FAT16 is that it has a fixed maximum number of clusters per partition, so as hard disks get bigger and bigger, the size of each cluster has to get larger. In a 2–GB partition, each cluster is 32 kilobytes, meaning that even the smallest file on the partition will take up 32 KB of space. FAT16 also doesn't support compression, encryption, or advanced security using access control lists.
  • FAT32 - FAT32 is the latest version of the FAT file system. It was introduced in 1996 for Windows 95 Service Pack 2 users and was the primary file system for consumer Windows versions through Windows ME. FAT32 supports drive sizes up to 8TB.
    FAT32 shares all of the other limitations of FAT16, and adds an important additional limitation—many operating systems that can recognize FAT16 will not work with FAT32—most notably Windows NT, but also Linux and UNIX as well. Now this isn't a problem if you're running FAT32 on a Windows XP computer and sharing your drive out to other computers on your network—they don't need to know (and generally don't really care) what your underlying file system is.



New Technology File System (NTFS):

NTFS Short for NT File System, is a high-performance and self-healing file system used in Windows Vista, Windows XP, 2003, 2000, NT and Windows 7, which supports file-level security, compression and auditing. It also supports large volumes and powerful storage solution such as RAID. NTFS supports hard drive sizes up to 256TB.

NTFS supersedes the FAT file system as the preferred file system for Windows operating systems. NTFS has several improvements over FAT and HPFS (High Performance File System) such as improved support for metadata and the use of advanced data structures to improve performance, reliability, and disk space utilization, plus additional extensions such as security access control lists (ACL) and file system journaling.

The most important new feature of NTFS is the ability to encrypt files and folders to protect your sensitive data.

The Advantages of NTFS:

The NTFS file system, introduced with first version of Windows NT, is a completely different file system from FAT. It provides for greatly increased security, file–by–file compression, quotas, and even encryption. It is the default file system for new installations of Windows XP, and if you're doing an upgrade from a previous version of Windows, you'll be asked if you want to convert your existing file systems to NTFS. Don't worry. If you've already upgraded to Windows XP and didn't do the conversion then, it's not a problem. You can convert FAT16 or FAT32 volumes to NTFS at any point. Just remember that you can't easily go back to FAT or FAT32 (without reformatting the drive or partition), not that I think you'll want to.

The NTFS file system is generally not compatible with other operating systems installed on the same computer, nor is it available when you've booted a computer from a floppy disk. For this reason, many system administrators, myself included, used to recommend that users format at least a small partition at the beginning of their main hard disk as FAT. This partition provided a place to store emergency recovery tools or special drivers needed for reinstallation, and was a mechanism for digging yourself out of the hole you'd just dug into. But with the enhanced recovery abilities built into Windows XP (more on that in a future column), I don't think it's necessary or desirable to create that initial FAT partition.