Disks and Formatting Ch 3

Moving-Head Disk Mechanism Operating System Concepts

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. Ch 3

Why Format a Disk? Disks used for: Permanent storage of data and programs Distributing data from one computer to another Making copies Ch 3

Why Format a Disk? Formatting (initializing) the disk: Process of preparing disk so that it is compatible with an operating system Ch 3

Why Format a Disk? All disks (including hard disks) must be formatted. Ch 3

Partitioning and Formatting Disks Hard disks must be: Partitioned Formatted with file system Ch 3

Partitioning and Formatting Disks Partition terms: Primary partition Partition table Volume Active partition Extended partition Ch 3

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 Ch 3

Partitioning and Formatting Disks File system: Organizational scheme of OS OS is what makes one computer compatible with another Ch 3

Partitioning and Formatting Disks Windows XP Professional supports four file systems: NTFS Three FAT file systems - FAT12 FAT16 FAT32 Ch 3

Partitioning and Formatting Disks Types of disk storage configuration: Basic disks Dynamic disks Ch 3

Structure of a Disk Two parts to formatting a disk: Low-level (physical) formatting High level (logical) formatting Ch 3

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 Ch 3

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. Ch 3

Windows XP Professional monitors status of all Structure of a Disk Windows XP Professional monitors status of all disk data sectors. Ch 3

Structure of a Disk One or more sectors are combined into logical units called clusters or allocation units. Ch 3

Structure of a Disk Cluster (allocation unit): Smallest unit that OS can work with Ch 3

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 Ch 3

Structure of a Disk Master Boot Record & Boot Sector First sector on logical drive Has table of drive’s characteristics Has bootstrap loader program Ch 3

Structure of a Disk Master Boot Record & Boot Sector All disks (including non-system disks) have a boot sector. Ch 3

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 Ch 3

Structure of a Disk Master Boot Record & Boot Sector NTFS non-system error messages: Invalid partition table Error loading operating system Missing operating system Ch 3

Structure of a Disk FAT16, VFAT & FAT32 FAT’s formatting program creates: Boot record File Allocation Table (2 copies) Root directory Ch 3

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 Ch 3

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 Ch 3

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 Ch 3

Structure of a Disk FAT16, VFAT & FAT32 FAT essential for: Managing data Following trail of clusters that make up a file Ch 3

Structure of a Disk FAT16, VFAT & FAT32 VFAT maintains backwards compatibility and accommodates long file names. Ch 3

Structure of a Disk FAT16, VFAT & FAT32 Enhancement of FAT file system Introduced to overcome limitations of VFAT Does not apply to floppy drives Ch 3

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 Ch 3

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 Ch 3

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 Ch 3

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 Ch 3

Structure of a Disk FAT16, VFAT & FAT32 FAT32 is best for many small files. FAT is best for mostly large files. Ch 3

Structure of a Disk The Root Directory Table that records information about each file on the disk Ch 3

Structure of a Disk The Root Directory Changes in root directory table make Windows XP Professional compatible with older Windows and DOS programs. Ch 3

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. Ch 3

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. Ch 3

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 Ch 3

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. Ch 3

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. Ch 3

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 Ch 3

Structure of a Disk Clusters and NTFS Uses FAT cluster scheme for allocating data. Has less overhead. Ch 3

Structure of a Disk Clusters and NTFS Table 3. 3 NTFS Cluster Size p Ch 3

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 Ch 3

NTFS New technology file system is file system that was introduced by 1993 MS Supports 256TB HD. PBS MFT SYSTEM FILE FILE AREA Ch 3

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 Ch 3

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 Ch 3

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 Ch 3

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 Ch 3

Structure of a Disk Deciding on a File System Formatting: Floppy disk - always FAT file system Hard disk - you decide Ch 3

Structure of a Disk Deciding on a File System Can convert FAT to FAT32/NTFS Cannot convert FAT32/NTFS to FAT Ch 3

Clarifying Procedures Procedural assumptions: System utility files subdirectory Type of disk Lab procedures Ch 3

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 268435456 65535 FILE NAME LENGTH UPTO255 255 8-3 BOOT SECTORE LOCATION FIRST AND LAST SECTOERE FIRST SECTOR Ch 3

Hard Disk Interface ATA SATA SCSI IDE PATA Ch 3

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 Ch 3

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. Ch 3

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 Ch 3

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. Ch 3