Logical organisation FAT 32
Reserved area |
FAT area |
Data area |
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Sektor 0 |
Sektor n |
Boot area |
FAT 1 |
FAT 2 |
Data incl. Root |
32++ sectors |
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- These structures are written while formatting the volume.
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FSINFO Sector
With FAT 32 the FSINFO sector is established
it´s written directly after the VBR (also after the copy)
it includes a signature (RRaA), the address of the next free cluster and the number of free clusters.
Be carefull:
These information is maybe not correct.
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FSINFO Sector
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Meta data of the file system
The meta data of the file system contain all information about the files and directories.
Particularly the number of the startcluster (content of the file) and also the timestamps and the attributes.
In FAT systems all these data are stored in directory structure an the FAT.
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Metadata of the file system
A directory entry is a structure which is created for every file and directory
The structure of directory can be stored somewhere in the data area because they are stored in cluster which are belongs to a directory.
A directory entry contains also the filename.
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Root Directory
•Normally begins just after the 2nd FAT
•Holds the subdirectory and file entries of the root
•For FAT12/16 the root directory is a fixed size
•For FAT 32 the root directory is a part of the data area and is chained via the FAT like a file
•32 bytes are reserved in the root directory for each entry
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Directory (Root) Entry |
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example of 6 entries |
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Starting |
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File name |
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Extension Attribute cluster |
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Filesize |
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Time Date |
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1 entry – 32 bytes
Subdirectories
•Contains directory- and file entries
•For each entry 32 bytes are reserved
•The first two entries are pointer to directories
a). = pointer to itself and
b).. = pointer to the parent cluster
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start cluster
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File Allocation Table (FAT)
•Central organizational structure of the file system
•For each cluster on the disc there is an entry in the FAT
•Each entry covers a number of sectors fixed by the operating system, called a cluster
•Contains information detailing where files are stored on the disc
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