Window NT File System

NTFS • Window NT can support three types of file system 1... FAT File System• Origin of FAT file system • A disk formatted with FAT is allocated in clusters size are determined by the

Window NT File System

JianJing Cao (#98284)

• Function of file system

1 Access method

2 File management

3 Auxiliary storage management

4 File integrity mechanisms

• Main types of the file system

1 FAT 2 HPFS 3 NTFS

• Window NT can support three types of file system

1 FAT 2 HPFS 3 NTFS

FAT File System

• Origin of FAT file system

• A disk formatted with FAT is allocated in

clusters (size are determined by the size of the volume )

• FAT is handled slightly differently under

NT

1 The generated 8.3 filename is stored along with the long

Drive Size FAT Type Sectors Cluster

(logical volume) Per Cluster Size - - - -

(Floppy Disks) 360K 12-bit 2 1K

720K 12-bit 2 1K

1.2 MB 12-bit 1 512 bytes 1.44 MB 12-bit 1 512 bytes 2.88 MB 12-bit 2 1K

(Hard Disks) 0 MB - 15 MB 12-bit 8 4K

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

Disadvantage of FAT File System

• It is advisable to not use FAT on partitions

that are greater than 200 megabytes FAT

partitions are limited in size to a maximum

of 4 Gigabytes (GB) under Windows NT

and 2 GB in MS-DOS

• It is not possible to set permissions on files

that are FAT partitions.

Disadvantage of FAT File System(Con.)

• Any FAT partitions that use DOS-based disk

compression (such as Stacker or

DriveSpace) will not have readable files

when running Windows NT

• The FAT file system is also prone to

fragmentation

HPFS File System

• Origin of HPFS file system

HPFS was introduced in 1990 as part of OS/2 Version 1.2

• Characters of HPFS

1 HPFS allowed for greater capacity of hard drives

2 HPFS also implements physical separation between files giving each file room for expansion, which would then

result in less chance of fragmentation

3 HPFS also introduced long filenames of up to 255

characters, along with other attributes

Disadvantage of HPFS

• Because of the overhead involved in HPFS, it is not

a very efficient choice for a volume of under

approximately 200 MB

• With volumes larger than about 400 MB, there will

be some performance degradation

• You cannot set security on HPFS under Windows

NT

• HPFS is only supported under Windows NT

versions 3.1, 3.5, and 3.51 Windows NT 4.0 can not access HPFS partitions

NTFS File System

• Origin of NTFS File System

With the introduction of Windows NT in 1992, Microsoft took the advanced capabilities of HPFS and went many steps further

The Goals of NTFS

• Reliability, which is especially desirable for

high end systems and file servers

• A platform for added functionality

• Support POSIX requirements

• Removal of the limitations of the FAT and

HPFS file systems

• Recoverability

1 NTFS is a recoverable file system because it keeps track

of transactions against the file system.

2 Under NTFS, a log of transactions against these

components is maintained so that CHKDSK need only roll back transactions to the last commit point in order to

recover consistency within the file system

• Removal of fatal single sector failures

Added Functionality

• NTFS provides a rich and flexible platform for

other file systems to be able to use

• NTFS fully supports the Windows NT security

model and supports multiple data streams No

longer is a data file a single stream of data

• Under NTFS, a user can add his or her own defined attributes to a file

user-POSIX Support

• NTFS is the most POSIX.1 compliant of the

supported file systems because it supports the following POSIX.1 requirements:

1 Case Sensitive Naming

2 Additional Time Stamp

3 Hard Links

Removing Limitations

• NTFS has greatly increased the size of files and

volumes, so that they can now be up to 16

exabytes

• NTFS has also returned to the FAT concept of

clusters in order to avoid HPFS problem of a fixed sector size

• In NTFS all filenames are Unicode based, and 8.3

• Security: NTFS uses the Windows NT object model to enforce

security An open file is implemented as a file object with a security descriptor that defines its security attributes.

• General indexing facility: NTFS associates a collection of attributes with each file The set of file descriptions in the file

management system is organized as a relational database, so that files can be indexed by any attribute.

Advantages of NTFS(Cont.)

• Multiple data stream: be used by remote

Macintosh systems to store and retrieve files

Disadvantages of NTFS

• It is not recommended to use NTFS on a

volume that is smaller than approximately

400 MB

• Currently, there is no file encryption built

into NTFS

• It is not possible to format a floppy disk

with the NTFS file system

Compare FAT and NTFS File System

• Compatibility

Only Windows NT supports NTFS partitions , Windows NT

and Windows 95 supports both NTFS and FAT

• Volume size

FAT supports partition sizes only up to 2 GB , the maximum

size of an NTFS partition is 16 EB

• Fault tolerance

Compare FAT and NTFS File System(Cont.)

• Security

NTFS has a built-in security system , FAT has no local

protection, it only has the share permission(protect the file from network)

• File compression

NTFS has its native support for file compression, It offers

you the chance to compress individual files and directories

of your choice

Compare FAT and NTFS File System(Cont.)

• The system partition

A better solution is to format your system partition as FAT

because NTFS partitions are accessible only via Windows

NT If you have a fatal error with Windows NT, you can’t

simply boot a system disk to a command prompt and fix a

problem on an NTFS partition

Does not support NetWare file and directory Supports NetWare file and directory

permissions during NetWare migration permission during migration