windows file systems

Windows File Systems

CGS2564

Who Cares?

C:\Documents\Taxes\Tax04.DOC

Formatting a Disk

Organizes tracks and sectors Sets up data structures on first track

Boot sector Root directory File allocation table (2)

Performs surface scan Checks for bad sectors

Disk Data Structures

Boot Sector

Information about the disk itselfOS name and version number.

Bytes per sector.

Sectors per cluster in the data area.

Number of reserved sectors.

Max. number of entries in the root directory.

Total number of sectors.

Media description (is this a hard disk?).

Number of sectors per FAT

Number of sectors per track.

Number of disk read heads.

Number of hidden sectors.

BOOT-strap program routine, which starts the operating system.

Disk Directory

A database of what is on the disk

File Allocation Table

A table of where files are located

Units on a Disk

Sector – the smallest unit of data storage 512 bytes (½ K)

“Allocation Unit” or “Cluster” The actual minimum space allotted to a file One or more sectors

Operating System File System(s)

DOS FAT16

Windows 95/98 FAT16, FAT32

Windows NT FAT16, NTFS

Windows 2000/XP FAT16, FAT32, NTFS

File Systems

FAT 16

Inefficient storage on large disks Size of FAT is fixed (216 entries) As disk capacity increases cluster size increases

Maximum disk size = 2 GB

FAT 32

More efficient storage on large disks Increased FAT size (232 entries) So cluster size can be decreased

Maximum disk size = 32 GB

NTFS

Uses Master File Table system (MFT) Even more efficient use of disk space Support for larger disk sizes

Windows File Protection feature (WFP) Prevents alteration or deletion of critical system files

Extended file attributes File permissions

But Not accessible by other file systems

NTFS Cluster Size

Volume Size FAT16 Cluster Size FAT32 Cluster Size NTFS Cluster Size

33MB – 64MB 1KB 512 bytes 512 bytes

65MB – 128MB 2KB 1KB 512 bytes

129MB – 256MB 4KB 2KB 512 bytes

257MB – 512MB 8KB 4KB 512 bytes

513MB – 1GB 16KB 4KB 1KB

1GB – 2GB 32KB 4KB 2KB

2GB – 4GB 64KB 4KB 4KB

4GB – 8GB Not supported 4KB 4KB

8GB – 16GB Not supported 8KB 4KB

16GB – 32GB Not supported 16KB 4KB

File Systems and Cluster Size

Slack Space

Wasted space not used by a file

Comparison of Cluster Usage

File Attributes

Archive Indicates if file has changed Used by backup programs

Read-only Protect file from being overwritten

Hidden Hide file from view

Additional NTFS Attributes Compress Encrypt Index

Filenames

Pre Windows 95 8 characters max No spaces

VFAT - Windows 95/98MFT – Windows 2000 Support for long filenames and spaces Stores two different filenames for each file

For backward compatibility

Long Filenames

Aliases

MS-DOS filenames for long filenames

File Path

Drive:\Directory\Subdirectory\Filename.ext

C:

Program Files My Documents WINNT

Assignments Projects

Assign03.doc

C:\My Documents\Assignments\Assign03.doc

Types of Files

User Data Files Created by user in application

Types of Files

Program Files Make up application itself

Types of Files

Executable files Actually “run” the program Extensions

.exe .com .bat

File Association

Or “Registered” File type Association between

A file extension

and

A file type

Then between

That file type

and

A program’s executable file

File Association

Extension Executable FileFile Type

.DOC WINWORD.EXEMICROSOFT WORD DOCUMENT

.BMP MSPAINT.EXEBITMAP IMAGE

.TXT NOTEPAD.EXETEXT DOCUMENT

Types of Files

Binary files Contain program instructions, document

information, formatting codes, etc. User data and program files

Pure text or “ASCII” files Contain only standard text characters User data and program files

How to tell? View in Notepad

Pure Text File

Binary File