Window NT File System

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Window NT File System

• JianJing Cao (98284)

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Contents

• Introduction
• FAT File System
• HPFS File System
• NTFS File System
• Compare FAT File System with NTFS File System

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Introduction

• 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

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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 filename
• 2. FAT partitions can be converted to NTFS

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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 16 MB - 127 MB
16-bit 4 2K 128
MB - 255 MB 16-bit 8 4K
256 MB - 511 MB 16-bit 16
8K 512 MB - 1023 MB 16-bit
32 16K 1024 MB - 2048
MB 16-bit 64 32K
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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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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.

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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

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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

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Advantage of HPFS

• HPFS is best for drives in the 200-400
• MB range.
• Less chance of fragment

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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.

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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

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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

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Reliability

• 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
• 1. Not using special objects on the disk and
  tracking and protecting all objects that are on
  the disk

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Reliability(Cont.)

• 2. Under NTFS, multiple copies (the number
  depends on the volume size) of the Master File
  Table are kept.
• Hot fixing
• Similar to OS/2 versions of HPFS, NTFS
  supports hot fixing.

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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
  user-defined attributes to a file.

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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

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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
  filenames are kept along with long filenames

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Advantages of NTFS

• Large disks and large files NTFS is best for use
  on volumes of about 400 MB or more
• Recoverability The recoverability designed into
  NTFS is such that a user should never have to run
  any sort of disk repair utility on an NTFS
  partition.
• 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.

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Advantages of NTFS(Cont.)

• Multiple data stream be used by remote
  Macintosh systems to store and retrieve files

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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

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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
• Windows NT offers software support for
  several alternate disk-access methods that
  increase speed and/or fault tolerance, While FAT
  does maintain two copies of the file-allocation
  table, in case one copy is damaged, its
  incapable of automatically fixing errors

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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

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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 cant simply
  boot a system disk to a command prompt and fix a
  problem on an NTFS partition
• Converting to NTFS
• In MS-DOS type command CONVERT drive
  /FSNTFS

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FAT

NTFS   Support by DOS, OS/2, Windows 95, and
Only supported under the NT OS Window
NT(Should be used if you need to Dual-boot and
access the partition from another OS)   No local
security available
Local security is available   Does not support
Macintosh files Support
Macintosh files   Does not support NetWare file
and directory Supports NetWare file and
directory permissions during NetWare migration
permission during migration   Does not
support NT file compression Support NT
file compression   Can be converted to NTFS at
any time NTFS can never be converted to
FAT. The
only way to go
from NTFS to FAT is to

backup the data, reformat the partition as

FAT, and then restore the data
to the new
FAT
partition.   Maximum partition size of 4GB
Maximum partition size of 16EB
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Reference
1. Window NT Server Unleashed   2. Operating
system Second Edition H. M. Deitel   3.
http//magic.hurrah.com/sabre/os/S3FileSystems/HP
FS/hpfs0.html   4. http//support.microsoft.com/su
pport/kb/articles/q100/1/18.asp   5. MCSE NT
Server 4 in the Enterprise Second Edition L.
Donald, J. Chellis