Tuesday, November 22, 2011

What are the file systems ??

What are file systems?

 Drives are storage media, which can hold a file system. When a disk is formatted in a drive, it becomes organized and prepared to receive data. When we format a disk, it receives a file system.Formatting can be compared to starting a library. You must install the book shelves and the catalogue system before any books are put in place. Once the library is ready, bring on the books! Similarly with a disk. When we format it, we "burn in" a file system to make it ready to receive data (files).

We can format with any one of several different file systems:

FAT (File Allocation Table), the original, old 16 bit DOS system is probably used in 90% of all PC’s. It is
also called FAT16 
FAT32 a new addition to FAT, which Microsoft introduced with Windows 95 B – The December -96 versi
HPFS (High Performance File System) from OS/2. It is an advanced 32 bit file system, which in all
respects is far superior to FAT, except for possible usage. It can only be used with OS/2.

NTFS from Windows NT. A 32 bit file system like HPFS, but not compatible with it. NTFS can,
unfortunately, only be used in Windows NT. If it was available for use in Windows 95, it would be far to
preferable to FAT and FAT32.

NetWare is a server operating system from Novell. It has its own 32 bit file system. For that reason, the
Novell server, contrary to NT or OS/2 servers, cannot be used as a work station. The file system is much
faster than FAT, but it works only with Novell servers (typically file servers).
UNIX servers have their own filing system. Here the use of upper/lower case in file naming is significant.l  
Read in the following pages about the concepts of these file systems.

Relationship between file system and operating system

We see that that the file system is an integral part of the operating system. An operating system can sometimes
work with different file systems:

Operating system                                               File system(s)
DOS                                                                   FAT16
Windows 95                                                       FAT16, FAT32    
(actually VFAT: Virtual FAT, which provides
access to use long file names)
Windows NT                                                      FAT16, NTFS
OS/2                                                                   FAT16, HPFS
Novell NetWare                                                  Own "brand name"

The file system is actually the interface between operating system and drives plus disks. When the user software such as MS Word, asks to read a file from the hard disk, the operating system (Windows 95 or NT) asks the file system (FAT or NTFS) to open the file:


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