Tuesday, November 23, 2010

File systems

File system (sometimes written as filesystem) is the term used to describe the method used to store files on disk drives and other storage media. There are many different file systems in common use.
  • FAT (for file allocation table) is one of the oldest file systems and was originally designed for use with floppy disks under MS-DOS. It is supported by all major operating systems and many other devices. Extended to allow use with hard drives, it is now rarely used due to a low limit on the maximum size of an individual drive or partition and the fact that file names are limited to eight characters plus a three character extension.
  • FAT32 is a development of FAT that is able to support larger drives and partitions and file names of up to 255 characters in total length. Introduced with Windows 95, it is falling out of use in computers as it is inefficient when used with large hard drives, lacks any access control features and is prone to corruption. However it is commonly used with memory cards (such as in digital cameras) and removable drives due to its simplicity and it is supported by most major operating systems not just Windows.
  • NTFS (for New Technology File System) is so named as it was introduced with Windows NT, the forerunner of Windows XP, Vista and Windows 7. There are many versions of NTFS, each introducing new features. NTFS includes many features considered necessary to support a modern operating system including access rights and encryption. It is fully supported only under Windows though Mac OS and Linux support read access to allow NTFS partitions on a dual boot system to be read.
  • HFS (for Hierarchical File System) was developed by Apple for use on Mac OS. There is also a newer version able to support larger files called HFS Plus. It is an advanced file system offering many of the same capabilities as NTFS but is only supported on Mac OS.
  • ISO 9660 is an International Standards Organization file system which is used on CDs, DVDs and other optical media. It was designed to be independent of operating system and is supported by all major operating systems.
  • UDF (Universal Disk Format) is a file system that is mostly used on DVDs and other high capacity optical media where it is replacing ISO 9660.

If you need to recover deleted files from a non-optical storage device then use a data recovery program written for the type of computer (operating system) that can read the device. So a Windows program like Uneraser will be able to recover files from a drive written by Windows and a Mac program like File Recovery for Mac will be able to recover files from a drive written by a Mac.

The file systems used for optical storage media are not generally supported by hard drive data recovery software so to recover files from CD and DVD you must use a specialized program such as IsoBuster.