THE FAT FILE SYSTEMS. FAT32 FAT16 FAT12

The File Allocation Table (FAT) file system is a simple file system originally designed for small disks and simple folder structures. The FAT file system is named for its method of organization, the file allocation table, which resides at the beginning of the volume. To protect the volume, two copies of the table are kept, in case one becomes damaged. In addition, the file allocation tables and the root folder must be stored in a fixed location so that the files needed to start the system can be correctly located.

A volume formatted with the FAT file system is allocated in clusters. The default cluster size is determined by the size of the volume. For the FAT file system, the cluster number must fit in 16 bits and must be a power of two.

 

Structure of a FAT Volume

The figure below illustrates how the FAT file system organizes a volume.

Figure 4-1

Table 4-1 Differences Between FAT Systems

System	Bytes Per Cluster Within File Allocation Table	Cluster limit
FAT12	1.5	Fewer than 4087 clusters.
FAT16	2	Between 4087 and 65526 clusters, inclusive.
FAT32	4	Between 65526 and 268,435,456 clusters, inclusive.

Wielkości klastrów w różnych systemach plików
Rozmiar partycji		FAT16	FAT32	NTFS
0 - 32	MB	0,5 kB	-	0,5 kB
33 - 64	MB	1 kB	-	0,5 kB
65 - 127	MB	2 kB	-	0,5 kB
128 - 255	MB	4 kB	-	0,5 kB
256 - 511	MB	8 kB	-	0,5 kB
512 - 1023	MB	16 kB	4 kB	1 kB
1 - 2	GB	32 kB	4 kB	2 kB
2 - 4	GB	64 kB	4 kB	4 kB
4 - 8	GB	-	4 kB	8 kB
8 - 16	GB	-	8 kB	16 kB
16 - 32	GB	-	16 kB	32 kB
pow 32	GB	-	32 kB	64 kB

    

NTFS vs FAT

Criteria	NTFS5	NTFS	FAT32	FAT16	FAT12
Operating System	Windows 2000 Windows XP Windows 2003 Server	Windows NT Windows 2000 Windows XP Windows 2003 Server	DOS v7 and higher Windows 98 Windows ME Windows 2000 Windows XP	DOS All versions of Microsoft Windows	DOS All versions of Microsoft Windows
Limitations
Max Volume Size	2TB	2TB	32GB for all OS. 2TB for some OS	2GB for all OS. 4GB for some OS	16MB
Max Files on Volume	Nearly Unlimited	Nearly Unlimited	4194304	65536
Max File Size	Limit Only by Volume Size	Limit Only by Volume Size	4GB minus 2 Bytes	2GB (Limit Only by Volume Size)	16MB (Limit Only by Volume Size)
Max Clusters Number	Nearly Unlimited	Nearly Unlimited	4177918	65520	4080
Max File Name Length	Up to 255	Up to 255	Up to 255	Standard - 8.3 Extended - up to 255	Up to 254
File System Features
Unicode File Names	Unicode Character Set	Unicode Character Set	System Character Set	System Character Set	System Character Set
System Records Mirror	MFT Mirror File	MFT Mirror File	Second Copy of  FAT	Second Copy of  FAT	Second Copy of  FAT
Boot Sector Location	First and Last Sectors	First and Last Sectors	First Sector and Copy in Sector #6	First Sector	First Sector
File Attributes	Standard and Custom	Standard and Custom	Standard Set	Standard Set	Standard Set
Alternate Streams	Yes	Yes	No	No	No
Compression	Yes	Yes	No	No	No
Encryption	Yes	No	No	No	No
Object Permissions	Yes	Yes	No	No	No
Disk Quotas	Yes	No	No	No	No
Sparse Files	Yes	No	No	No	No
Reparse Points	Yes	No	No	No	No
Volume Mount Points	Yes	No	No	No	No
Overall Performance
Built-In Security	Yes	Yes	No	No	No
Recoverability	Yes	Yes	No	No	No
Performance	Low on small volumes High on Large	Low on small volumes  High on Large	High on small volumes Low on large	Highest on small volumes Low on large	High
Disk Space Economy	Max	Max	Average	Minimal on large volumes	Max
Fault Tolerance	Max	Max	Minimal	Average	Average

    

Struktura wolumenu NTFS

File Attributes Defined by NTFS

Attribute Type	Description
Standard Information	Includes information such as timestamp and link count.
Attribute List	Lists the location of all attribute records that do not fit in the MFT record.
File Name	A repeatable attribute for both long and short file names. The long name of the file can be up to 255 Unicode characters. The short name is the 8.3, case-insensitive name for the file. Additional names, or hard links, required by POSIX can be included as additional file name attributes.
Security Descriptor	Describes who owns the file and who can access it.
Data	Contains file data. NTFS allows multiple data attributes per file. Each file typically has one unnamed data attribute. A file can also have one or more named data attributes, each using a particular syntax.
Object ID	A volume-unique file identifier. Used by the distributed link tracking service. Not all files have object identifiers.
Logged Tool Stream	Similar to a data stream, but operations are logged to the NTFS log file just like NTFS metadata changes. This is used by EFS.
Reparse Point	Used for volume mount points. They are also used by Installable File System (IFS) filter drivers to mark certain files as special to that driver.
Index Root	Used to implement folders and other indexes.
Index Allocation	Used to implement folders and other indexes.
Bitmap	Used to implement folders and other indexes.
Volume Information	Used only in the $Volume system file. Contains the volume version.
Volume Name	Used only in the $Volume system file. Contains the volume label.

 Pliki systemowe

0 Informacja MFT Podstawowy zapis danych wszystkich folderów i plików

1 Informacja MFT Kopia pierwszego zapisu

2 Plik protokołu Służy do przywrócenia spójności NTFS w następstwie błędów systemu

3 Informacja o woluminie Rozmaite informacje, takie jak nazwa i wersja woluminu

4 Definicje atrybutów Nazwy, liczby i opisy atrybutów pliku

5 Indeks katalogu głównego Dane katalogu głównego

6 Bitmapa klastra Pokazanie wolnych klastrów

7 Sektor startowy Zawiera program startujący, pomiędzy innymi elementami

8 Uszkodzone sektory Informacja o uszkodzonych sektorach

9 Plik kopii zapasowej Opis kopii zapasowej dla wszystkich plików

10 Konwerter Tłumaczy małe litery na Unicode

11 Rozszerzenia NTFS Różne funkcje dodatkowe

12 do 15 Wolna przestrzeń

BOOT sektor

(do 16 sektorów)

MFT

Pliki systemowe

(1MB)

Dane

Obszar plików

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