Booting from a Disk in Windows 2000 Windows 2000 places its boot code in the first sector on the hard disk (master boot record). Disk divided into more than one partitions with one as boot partition, which contains OS and device drivers. Operating System Concepts with Java – 8th Edition 12.19 Silberschatz, Galvin and Gagne ©2009
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File system implementation Physical disks     Divided into one or more “partitions” (logical, separate disks). Each partition can have its own file system. Sector 0 = MBR (master boot record)     List of partitions (start and ends) Indicates boot partition Every partition has a boot block (although it may be empty) Boot steps: 1. 2. 3. boot code in MBR executes reads in boot block code of boot partition and executes it boot block code boots OS code in partition
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C:\UMBC\331\java> java.ext.dirs=C:\JDK1.2\JRE\lib\ext java.io.tmpdir=C:\WINDOWS\TEMP\ os.name=Windows 95 java.vendor=Sun Microsystems Inc. java.awt.printerjob=sun.awt.windows.WPrinterJob java.library.path=C:\JDK1.2\BIN;.;C:\WINDOWS\SYSTEM;C:\... java.vm.specification.vendor=Sun Microsystems Inc. sun.io.unicode.encoding=UnicodeLittle file.encoding=Cp1252 java.specification.vendor=Sun Microsystems Inc. user.language=en user.name=nicholas java.vendor.url.bug=http://java.sun.com/cgi-bin/bugreport... java.vm.name=Classic VM java.class.version=46.0 java.vm.specification.name=Java Virtual Machine Specification sun.boot.library.path=C:\JDK1.2\JRE\bin os.version=4.10 java.vm.version=1.2 java.vm.info=build JDK-1.2-V, native threads, symcjit java.compiler=symcjit path.separator=; file.separator=\ user.dir=C:\UMBC\331\java sun.boot.class.path=C:\JDK1.2\JRE\lib\rt.jar;C:\JDK1.2\JR... user.name=nicholas user.home=C:\WINDOWS C:\UMBC\331\java>java envSnoop -- listing properties -java.specification.name=Java Platform API Specification awt.toolkit=sun.awt.windows.WToolkit java.version=1.2 java.awt.graphicsenv=sun.awt.Win32GraphicsEnvironment user.timezone=America/New_York java.specification.version=1.2 java.vm.vendor=Sun Microsystems Inc. user.home=C:\WINDOWS java.vm.specification.version=1.0 os.arch=x86 java.awt.fonts= java.vendor.url=http://java.sun.com/ user.region=US file.encoding.pkg=sun.io java.home=C:\JDK1.2\JRE java.class.path=C:\Program Files\PhotoDeluxe 2.0\Adob... line.separator=
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Basic Disks (5 of 7) • Primary and extended partitions on MBR disks • A primary partition is one from which you can boot an operating system • At least one primary partition must be marked as active - Only one primary partition can be active at a given time • The active partition is the partition where your computer will look for the hardwarespecific files to start the operating system • An extended partition is created from space that is not yet partitioned • The purpose of an extended partition is to enable you to exceed the four-partition limit of a basic disk • Only one extended partition can exist on a single basic disk • A computer with multiple partitions boots from the partition that is designated as the active partition • Must also be the system partition © 2018 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 8
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Disk Management     Low-level formatting, or physical formatting — Dividing a disk into sectors that the disk controller can read and write  Each sector can hold header information, plus data, plus error correction code (ECC)  Usually 512 bytes of data but can be selectable To use a disk to hold files, the operating system still needs to record its own data structures on the disk  Partition the disk into one or more groups of cylinders, each treated as a logical disk  Logical formatting or “making a file system”  To increase efficiency most file systems group blocks into clusters  Disk I/O done in blocks  File I/O done in clusters Boot block initializes system  The bootstrap is stored in ROM  Bootstrap loader program stored in boot blocks of boot partition Methods such as sector sparing used to handle bad blocks Operating System Concepts Essentials – 8 th Edition 11.28 Silberschatz, Galvin and Gagne ©2011
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How Partitions and File Systems Work • Hard drives are further divided into one or more partitions (can have up to four in Windows) – Maps of the partitions are kept in a partition table in the first sector of the drive called the Master Boot Record (MBR) – Can have up to three primary partitions (also called volumes) – A fourth partition (called extended partition) can hold one or more volumes called logical drives A+ Guide to Managing & Maintaining Your PC, 8th Edition © Cengage Learning 2014 37
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Basic Disks (3 of 7) • MBR and GPT support • When a drive is partitioned, a Master Boot Record (MBR) and a partition table are created - At the beginning track and sectors on the disk • The MBR is located in the first sector and track of the hard disk - Has startup information about partitions and how to access the disk • The partition table contains information about each partition created • Globally Unique Identifier (GUID) Partition Table or GPT - A newer way to partition disks, without imposing the same type of limits on the number of partitions as with MBR • GPT disks store partition information in each partition using main and backup tables © 2018 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 6
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Disk Management  Low-level formatting, or physical formatting — Dividing a disk into sectors that the disk controller can read and write  To use a disk to hold files, the operating system still needs to record its own data structures on the disk  Partition the disk into one or more groups of cylinders  Logical formatting or “making a file system”  To increase efficiency most file systems group blocks into clusters  Disk I/O done in blocks  File I/O done in clusters  Boot block initializes system  The bootstrap is stored in ROM  Bootstrap loader program  Methods such as sector sparing used to handle bad blocks Operating System Concepts with Java – 8th Edition 12.18 Silberschatz, Galvin and Gagne ©2009
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Multiple-partition allocation  Multiple-partition allocation  Degree of multiprogramming limited by number of partitions  Variable-partition sizes for efficiency (sized to a given process’ needs)  Hole – block of available memory; holes of various size are scattered throughout memory  When a process arrives, it is allocated memory from a hole large enough to accommodate it  Process exiting frees its partition, adjacent free partitions combined  Operating system maintains information about: a) allocated partitions b) free partitions (hole) Operating System Concepts – 9th Edition 8.23 Silberschatz, Galvin and Gagne ©2013
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Disk Structure  Disk can be subdivided into partitions  Disks or partitions can be RAID protected against failure  Disk or partition can be used raw – without a file system, or formatted with a file system  Partitions also known as minidisks, slices  Entity containing file system known as a volume  Each volume containing file system also tracks that file system’s info in device directory or volume table of contents  As well as general-purpose file systems there are many special-purpose file systems, frequently all within the same operating system or computer Operating System Concepts – 8th Edition 10.18 Silberschatz, Galvin and Gagne ©2009
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