Partitions and File Systems

Partitions and File Systems

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Partitions

A partition is a logical section of a hard disk drive. Creating a partition on a hard disk drive enables the hard disk drive to support separate file systems. Partitions can either be primary or extended. A hard disk drive can be divided into multiple logical partitions. However, it is recommended to have as few partitions as possible.

In DOS and Windows, a partition is referred to by a drive letter, such as C: or D:. As a rule, the operating system assigns the drive letter C: to the primary partition on the first hard disk drive, and then goes on to search for other primary partitions that may exist on the other hard disk drives. If the operating system finds more primary partitions on other disks, it first assigns the next drive letters in the series, to them. Then, the operating system goes on to assign letters to logical drives (in extended partitions) on each hard disk drive, continuing the series further. Drive letters A: and B: are reserved for floppy disk drives.

Types of Partitions: The following are the different types of partitions:

Active Partition: An active partition is one that is read at startup and is expected to have the necessary system files on it to boot the computer. If a partition is not set as Active, the computer will not boot from the hard disk drive. There can be only one active partition in one physical hard disk drive. Only the primary partition can be marked as an active partition.

System Partition: A system partition contains hardware-specific files used in loading and initializing the operating system. Only a primary partition can be used as a system partition. In Windows NT, system partition contains boot files namely NTLDR, NTDETECT.COM, and BOOT.INI. It may also contain the BOOTSECT.DOS and NTBOOTDD.SYS files.

Boot Partition: A boot partition contains operating system files and other support files needed by the operating system. It is also used to start the operating system. A primary partition or a logical drive in an extended partition can be used as a boot partition. Boot partition and system partition can be the same partition. In Windows NT, boot partition contains the operating system and NTOSKRNL.EXE.

Note: The system partition and the boot partition can be two different partitions, and can also be located on two different physical disks.

A partition is normally accomplished by running the FDISK program that comes with the operating systems. It is used to create, change, delete, or display current partitions on the hard disk. Each of the defined disk spaces (primary partition, extended partition or logical drive) is assigned a drive letter. After the hard disk is partitioned, it is formatted with a file system and the operating system is installed on it. These three procedures make a computer ready for use.

Caution! Using FDISK for removing or creating a partition on a hard disk drive destroys any data contained on that partition or on that part of the hard disk drive.


File Systems

In a computer, a file system refers to the methods and data structures that an operating system uses to keep track of files on a disk or partition. It is the way in which files are named and logically placed for storage and retrieval. Most of the operating systems, such as Windows, UNIX, and Linux use file systems in which files are placed in a hierarchical (tree) structure. File systems also specify conventions for naming files, such as the maximum number of characters in a name, the characters that can be used, the length of a file name suffix etc. File systems include a format for specifying the path to a file through the structure of directories.

File systems supported by Windows: Windows operating systems support the following file systems:

FAT: The FAT or FAT16 file system is used to store data on a disk. The FAT file system is better suited for hard disk drives or partitions less than 200MB. It supports a single partition up to a maximum size of 2GB.

FAT32: The FAT32 file system is an enhancement of the FAT16 file system. FAT32 can support hard disk drives larger than 2GB (maximum 2TB) without having to use multiple partitions. It is more efficient as compared to 16-bit FAT on larger disks, as FAT32 decreases the cluster size on large hard disk drives, thereby reducing the amount of unused space.

NTFS: NTFS file system supports volumes up to 2EB. It supports compression on volumes, folders, and files.

The major characteristics of these files systems are as follows:

File Systems	Supported By	Long Filename Support	File-level Security Support
File Allocation Table (FAT)	DOS, Windows 9x/ME/NT/XP/2000	No	No
File Allocation Table, 32 BIT (FAT32)	Windows 95 OSR2/98/ME/XP/2000	Yes	No
Windows NT File System (NTFS)	Windows NT/XP/2000	Yes	Yes

Advantages of FAT32 over FAT16

The benefits of using FAT32 file system over FAT16 include the following:

• FAT32 is more efficient (sometimes 20-30 percent) than a 16-bit FAT on larger disks.


• FAT32 can support larger than 2GB partitions. It supports drives of up to 2TB (terabytes) in size.

Advantages of NTFS file system over FAT file system

The benefits of using NTFS file system over FAT file system include the following:

• NTFS is a transactional file system and can automatically recover from errors.
• Access to files can be secured and files and folders can be encrypted.


• Support for large hard disks, theoretically up to 2EB (Exabyte) and practically up to 2TB. The maximum drive size for NTFS is much larger than file allocation table (FAT).

Converting FAT16 file system to FAT32 file system

The CVT1.EXE utility converts a hard disk drive from FAT16 to FAT32.

The following points should be kept in mind before converting a hard disk drive from FAT16 to FAT32:

• Once converted to FAT32, the hard disk drive cannot revert to FAT16.


• A compressed drive cannot be converted.


• Removable disks that have been formatted with FAT32 may not work with other operating systems.


• Dual-boot to older operating systems will not be possible after a conversion to FAT32.

Converting FAT file system to NTFS file system

The CONVERT utility is used to convert a hard disk drive or partition formatted with the FAT file system to NTFS file system.

Syntax:

CONVERT <drive letter>: /fs:ntfs

Note: A hard disk drive formatted with NTFS file system cannot be reverted to FAT.

File-level permissions: File-level permissions allow administrators to set permissions to individual files. Only NTFS file system supports file-level permissions. When files are copied or moved from one location to another, the file permissions change as follows:

Source and Destination	Copy	Move
Within the same NTFS partition	Files inherit permissions of the destination directory.	Files keep permissions of the source directory.
Between different NTFS partitions	Files inherit permissions of the destination directory.	Files inherit permissions of the destination directory.
From NTFS partition to FAT partition	Files lose all the permissions.	Files lose all the permissions.
From FAT partition to NTFS partition	Files inherit permissions of the destination directory.	Files inherit permissions of the destination directory.

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