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FILE SYSTEMS

BY

K.Krishna Kumar(10mse1081)

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File system

In a computer, a file system (sometimes written

filesystem) is the way in which files are named and

where they are placed logically for storage and retrieval.

File systems specify convention for naming files.

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A file system defines the structure and the rules used to

read, write, and maintain information stored on a disk. Which system used is determined by;

Hardware

Software

Security needs

Need for a dual-booting system

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File Names

1 to 255 characters in length

This includes the path

You can use uppercase and lowercase (case-aware, butnot case-sensitive)

You can use spaces and periods

You cannot use these characters:

/ \ : * ? < > |

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File Names continued

Filenames consist of two parts

Main part of filename

Identifies the contents of the file File extension

Identifies the file type

The last period separates the file extension from the

main part of the filename. Windows typically associates a file extension with an

application installed on a computer

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Some of the file systems

FAT

NTFS

EXT

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FAT???

file allocation table where the OS records how the disk

space is used

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File Systems

FAT12:The earliest version the file system, FAT12allows a partition to contain up to 4096MB/ (212)clusters.

FAT 16: oldest, created for DOS, supported by mostOSs, cannot be installed on partitions larger than 2 GB, or onhard drives larger than 4GB.

FAT 32: supports disks from 512MB to 2TB, compatiblewith Windows 98 and up

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Advantages of FAT File System

The FAT file system is best for drives and/or partitionsunder approximately 200 MB

It is better to format system partition as FAT

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Disadvantage of FAT File System

It is not better to use FAT on partitions that are greaterthan 200 megabytes.

FAT partitions are limited in size to a maximum of 4Gigabytes (GB) under Windows NT and 2 GB in MS-DOS.

The FAT file system is also prone to fragmentation

.

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NTFS(new technology file system) better file security

(Encrypting File System), disk compression, Disk Quotafeatures, reliability and stability. NTFS volumes can not be

accessed by DOS, or Windows 95 or Windows 98.

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Advantages of NTFS

Large disks and large files: NTFS is best foruse on volumes of about 400 MB or more

Security:NTFS uses the Windows NT object modelto enforce security. An open file is implemented as a fileobject with a security descriptor that defines its security

attributes.

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Disadvantages of NTFS

It is not recommended to use NTFS on a volume that issmaller than approximately 400 MB

Currently, there is no file encryption built into NTFS

It is not possible to format a floppy disk with the NTFSfile system

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Fat to NTFS

Convert.exe helps to convert from fat to NTFS

No data is lost

NTFS to FAT conversion requires reformatting hard drive

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OS and File System Compatibility

Operating System FAT16 FAT32 NTFS

Windows XP

Windows 2000

Windows NT

Windows 95, 98, ME

Windows 95

MS-DOS

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Third Extended File System

Is a journaled file system that is commonly used by theLinux kernel

Ajournaling file system is a file system that logschanges to a journal before actually writing them to themain file system.

Default file system for many popular Linux distributions..

Maximum individual file size can be from 16 GB to 2 TB Overall ext3 file system size can be up to 32 TB

ext3

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ext4

Starting from Linux Kernel 2.6.19 ext4 was available.

Supports huge individual file size and overall file systemsize.

Maximum individual file size can be up to 16 TB.

Maximum ext4 file system size is 1 EB ;1 EB = 1024 PB(petabyte). 1 PB = 1024 TB (terabyte).

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Thank You !!!