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.

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2. File Systems
 The hard disks and other media provide the
physical space for storing data.
 The file system provides the logical structure
of organizing data on a physical drive.
 It provides the mechanism to locate data any
where on a given disk or drive.
 It provides the hierarchical structure of
directories in which individual files are stored.
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Description of File System

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Type of File System
File system types can be classified into disk file systems,
network file systems, and flash file systems.
A dish file system is a file system designed for the storage
of files on a data storage device, most commonly a dish
drive e.g.- FAT, NTFS, etx2, ext3 etc.
A network file system is a file system that acts as a client
for a remote file access protocol, providing access to file
on a sever e.g.- NFS, SMB etc.
A flash file system is a file system designed for storing files
on flash memory devices.

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Dish File Systems
FAT ( 12, 16, 32 )
exFAT
NTFS
HFS
HFS+
HPFS
UFS
Ext ( 2, 3, 4 )
XFS

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FAT File System

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FAT ( File Allocation Table )
 File Allocation Table is a file system developed by
Microsoft for MS DOS And primary file system for
consumer versions of Microsoft Windows up to
and including Windows me.
 The various FAT systems are:
FAT12 - used on volumes smaller than 16MB (Floppies)
FAT16 - used on volumes 16MB to 2GB (Hard Drives)
FAT32 - used on volumes 512MB to 2TB (Hard Drives)

8. File Allocation Table
The file allocation table (FAT) is a list of numerical
entries - describing how each cluster in the
partition is allocated.
Each cell of the table corresponds to a single
cluster on the disk.
The number stored in that cell indicates where the
next cluster of the file is located.
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9. File Allocation Table
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10. Clusters (Allocation Units)
A cluster is equal to one or more 512-byte sectors, in
a power of two.
Having more than one sector per cluster reduces
the size and processing overhead of the FAT and
enables the operating system to run faster because
it has fewer individual units to manage.
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12. Floppy Cluster Sizes
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FAT16 Cluster Sizes

13. FAT32 Cluster Sizes
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14. FAT32 Cluster Sizes
Cluster Size = size of the partition / 221
= size of the partition / 2,097,152
A 8GB partition will have cluster of size:
= 8GB / 2,097,152
= 8 x 1024 x 1024 kB / 2,097,152
= 4 kB
The cluster size will be multiples (1, 2, 4, 8, 16, 32, 64) of
512 Bytes.
So, the next size is 8kB for the partitions 8GB ~16GB.
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Advantages of FAT File System
 The FAT File system is best for drives and/or
partitions under approximately 200 MB.
 It is better to format system partition as FAT

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Disadvantages of FAT File System
It is not better to use FAT on partitions that
are greater than 200MB. FAT partitions are limited
in size to a maximum of 4G under the windows NT
and 2GB in MS-DOS.
Any FAT partitions that use DOS-based dish
compression (such as Drive Space )Will not
have readable files when files when running
windows NT.
The FAT File System is also prone to fragmentation.

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