1. Disks and
Formatting
Ch 3

2. Moving-Head Disk Mechanism
Operating System Concepts

3. Formatting
Formatting is process of preparing the blank hard disk for a particular operating system
Formatting a hard disk puts special magnetic marks of track sectors on disk.
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4. Why Format a Disk? Disks used for:
Permanent storage of data and programs
Distributing data from one computer to another
Making copies
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5. Why Format a Disk? Formatting (initializing) the disk:
Process of preparing disk so that it is compatible with an operating system
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6. Why Format a Disk? All disks (including hard disks) must be formatted.
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7. Partitioning and Formatting Disks
Hard disks must be:
Partitioned
Formatted with file system
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8. Partitioning and Formatting Disks
Partition terms:
Primary partition
Partition table
Volume
Active partition
Extended partition
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9. Partitioning and Formatting Disks
Dual booting system:
Create partition for each OS
Only one OS active at a time
Each OS formats disks in own way
Precautions in running multiple OS
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10. Partitioning and Formatting Disks
File system:
Organizational scheme of OS
OS is what makes one computer compatible with another
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11. Partitioning and Formatting Disks
Windows XP Professional supports four file systems:
NTFS
Three FAT file systems -
FAT12
FAT16
FAT32
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12. Partitioning and Formatting Disks
Types of disk storage configuration:
Basic disks
Dynamic disks
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13. Structure of a Disk Two parts to formatting a disk:
Low-level (physical) formatting
High level (logical) formatting
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14. Structure of a Disk Low-level (physical) formatting:
Sequentially numbers tracks and sectors
Identifies each track and sector
Disk is physically prepared to hold data
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15. Structure of a Disk High-level (logical) formatting:
Determines how OS uses a disk
Builds structure to keep track of location of files
Done so files can be stored and retrieved.
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16. Windows XP Professional monitors status of all
Structure of a Disk
Windows XP Professional monitors status of all
disk data sectors.
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17. Structure of a Disk One or more sectors are
combined into logical units
called clusters or allocation units.
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18. Structure of a Disk Cluster (allocation unit):
Smallest unit that OS can work with
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19. Structure of a Disk Master Boot Record & Boot Sector
Master boot record (MBR):
First part of hard disk
Locates bootable partition of hard disk and gives control over to it
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20. Structure of a Disk Master Boot Record & Boot Sector
First sector on logical drive
Has table of drive’s characteristics
Has bootstrap loader program
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21. Structure of a Disk Master Boot Record & Boot Sector
All disks (including non-system
disks) have a boot sector.
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22. Structure of a Disk Master Boot Record & Boot Sector
FAT non-system error messages:
Non-system disk or disk error
Replace disk and press any key when ready
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23. Structure of a Disk Master Boot Record & Boot Sector
NTFS non-system error messages:
Invalid partition table
Error loading operating system
Missing operating system
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24. Structure of a Disk FAT16, VFAT & FAT32
FAT’s formatting program creates:
Boot record
File Allocation Table (2 copies)
Root directory
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25. Structure of a Disk FAT16, VFAT & FAT32 Fig 3
Structure of a Disk FAT16, VFAT & FAT32 Fig 3.1 Logical Structure of a Disk p. 100
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26. Structure of a Disk FAT16, VFAT & FAT32
FAT is a map of disk’s data clusters.
FAT number indicates status of cluster.
Numbers in FAT link clusters that belong to same file
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27. Structure of a Disk FAT16, VFAT & FAT32 Table 3
Structure of a Disk FAT16, VFAT & FAT32 Table 3.1 Cluster Size and Disk Size p. 100
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28. Structure of a Disk FAT16, VFAT & FAT32
FAT essential for:
Managing data
Following trail of clusters that make up a file
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29. Structure of a Disk FAT16, VFAT & FAT32
VFAT maintains
backwards compatibility and
accommodates long file names.
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30. Structure of a Disk FAT16, VFAT & FAT32
Enhancement of FAT file system
Introduced to overcome limitations of VFAT
Does not apply to floppy drives
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31. Structure of a Disk FAT16, VFAT & FAT32 Table 3
Structure of a Disk FAT16, VFAT & FAT32 Table 3.2 Comparison of FAT and FAT32 p. 101
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32. Structure of a Disk FAT16, VFAT & FAT32
Movable Root Directory
Can be located anywhere on hard disk
Can use backup copy of FAT
Internal backup copy of some critical FAT data structures
Entries in Root Directory limited
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33. Structure of a Disk FAT16, VFAT & FAT32
With smaller clusters:
More clusters on partition
FAT larger - store more data
Takes longer to locate/access file
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34. Structure of a Disk FAT16, VFAT & FAT32
With larger clusters:
Table smaller
Takes less time to locate/access file
Increases wasted disk space from cluster overhang
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35. Structure of a Disk FAT16, VFAT & FAT32
FAT32 is best for many small files.
FAT is best for mostly large files.
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36. Structure of a Disk The Root Directory
Table that records information about each file on the disk
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37. Structure of a Disk The Root Directory
Changes in root directory table make Windows XP Professional compatible with older Windows and DOS programs.
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38. Structure of a Disk FAT and the Root Directory
Root directory tells what is on the disk.
FAT tells where data is on the disk.
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39. Structure of a Disk FAT and the Root Directory
Number in FAT points to next cluster that holds data in file.
EOF (end-of-file) marker indicates there is no more data in file.
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40. Structure of a Disk FAT and the Root Directory Fig 3
Structure of a Disk FAT and the Root Directory Fig 3.2 The Root Directory and FAT p. 103
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41. Structure of a Disk Data Portion or the Files Area
Largest part of disk is used for storing files.
Space is allocated to files on an as-needed basis.
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42. Structure of a Disk NTFS
File system used determines OS advanced features available to user.
For disk security, performance, and efficiency use NTFS file system.
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43. Structure of a Disk NTFS
Advantages of NTFS:
Secure file system
Efficient storage of data
Faster file access
Better data recovery
Can compress files/assign disk quotas
Encryption of files
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44. Structure of a Disk Clusters and NTFS
Uses FAT cluster scheme for allocating data.
Has less overhead.
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45. Structure of a Disk Clusters and NTFS Table 3. 3 NTFS Cluster Size p
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46. Structure of a Disk Clusters and NTFS Fig 3
Structure of a Disk Clusters and NTFS Fig 3.4 Structure of an NTFS Volume p. 106
PBS
FAT1
FAT2
(D.F)
Root
Folder
Other Folders
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47. NTFS
New technology file system is file system that was introduced by 1993 MS
Supports 256TB HD.
PBS
MFT
SYSTEM FILE
FILE
AREA
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48. Structure of a Disk Master File Table (MFT)
Database of all files in system
Used by NTFS to track all files and directories in a volume
Dynamic
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49. Structure of a Disk Master File Table (MFT)
Adds security descriptor attribute to file system
Data in file considered to be attribute of file
Allows fast access to files
Eliminates file fragmentation
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50. Structure of a Disk Master File Table (MFT)
Attribute stored in MFT considered resident attribute
Any resident forced out to an extent is nonresident attribute
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51. Structure of a Disk Master File Table (MFT)
Folders treated as files in NTFS:
Small folder - Index Root attribute
Folder entries will fit into MFT - new extent nonresident attribute called index buffer
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52. Structure of a Disk Deciding on a File System
Formatting:
Floppy disk - always FAT file system
Hard disk - you decide
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53. Structure of a Disk Deciding on a File System
Can convert FAT to FAT32/NTFS
Cannot convert FAT32/NTFS to FAT
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54. Clarifying Procedures
Procedural assumptions:
System utility files subdirectory
Type of disk
Lab procedures
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55. Compare FAT 16 ,32,NTFS Criteria NTFS FAT32 FAT16 Os XP,2000,NT
DOS
VOLUME SIZE
2TB
2GB
MAX FILE VOLUME
UNLIMITED
65000
Volume size
4GB
CLUSTER
SIZE
65535
FILE NAME LENGTH
UPTO255
255
8-3
BOOT SECTORE LOCATION
FIRST AND LAST SECTOERE
FIRST SECTOR
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56. Hard Disk Interface
ATA
SATA
SCSI
IDE
PATA
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57. ATA ATA1 ATA2 ATA3 ATA-4 8.3 MBPS 16.6MBPS 16MBPS 33MBPS
16BIT DATA WIDTH
16 BIT DATA WIDTH
16 BIT DATA
40 PIN
2 DEVICE
4 DEVICES
4 DEVICE DMA CHANNEL
2 ULTRA
DMA 0,1,2 MODES
PIO MODES FOR BUS ERROR CORRECTION
AND MULTIMODE DMA
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58. PATA
Parallel advanced technology attachment is standard interface for connecting storage device for hard disk and CD-ROM.
It allow 18 inches 46cm.
Based on IBM PC.
designed for pc,notebook.
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59. Scsi interface
SCSI is set of standards for physically connecting transferring data between computers
Fast and wide data path
Supports 7 peripherals
100MBPS TO 160 MBPS
PLUG AND PLAY
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60. SAS INTERFACE
Point to point serial protocol that moves data to and from computer.
SAS offers more capacity easier scalability
Enhanced security system.
8m cables.
Used sata protocol.
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