meljun cortes computer organization_lecture_chapter_10

Chapter 10Implementing Hard Drives

MELJUN CORTESMELJUN CORTES

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

OverviewIn this chapter, you will learn to

Explain the partitions available in Windows

Discuss the formatting options

Partition and format a hard drive

Maintain and troubleshoot a hard drive

Hard Drive Partitions


Partitioning Process of electronically subdividing the

physical hard drives Windows assigns them names such as C: or D:

A hard drive must have at least one partition

Partitioning enables organization of a drive that suits your personal taste

• One physical drive– One or more logical

partitions

EssentialsCompTIA A+Essentials


Basic DisksMaster boot record (MBR)

Small amount of code that takes control of boot process

Looks in partition table for partition holding valid operating system

MBR and partition table stored in boot sector

Only one MBR per disk


Basic DisksSupport up to four partitions

Can have four primary partitions or three primary partitions and one extended partition

Primary partition—bootable

Extended partitions—non-bootableCan hold multiple logical drives lettered D: to

Z:


Partitioning Primary partitions:

Store bootable operating system

Disk can have up to four primary partitions

Active partition is one currently booted to

Only one primary partition can be active at a time

Extended partitions:Extended partitions are

not bootable

Disk can have only one extended partition

They can be divided into many logical drives

Strength is number of drive letters that can be used, D: to Z:


Primary PartitionsCan be used for dual-boot or multi-boot

configurations

More than one bootable partition

Third-party tools available to identify primary partitions and provide choices

Partition currently booted to is marked as active partition


Dynamic DisksNew since Windows 2000 (Server and

Workstation)Not available in XP Home Edition

Partitions called simple volumesNo limitation on number of volumes

Added capabilitiesRAID 0, 1, 5 on Windows Server productsRAID 0 on Windows desktop productsExtended and spanned volumes

RAID covered in Chapter 9Other volumes covered in more depth later in chapter


Other PartitionsHidden partition

Primary partition hidden from OSUsed to hide a backup copy of OS

Swap partitionOnly on Linux and BSD systemsEntire partition that works like page file in

Windows


When to PartitionOlder OSs required partitioning before

installationCommand-line program called FDISK

Windows 2000 and above include partition tool in install program


When to PartitionAfter installation

Windows 2000 and above use GUI called Disk Management

Third-party tools available: GParted (Linux tool

that works on Windows partitions)

Partition Magic


Hard Drive FormattingFormatting configures a partition to hold

files and folders suitable to the OS

Two major functions of formatting Creates a file systemCreates a root directory


File SystemsWindows supports three different file

systems:

FAT16 (often called just FAT)

FAT32

NTFS


File Allocation Table (FAT)File allocation table (FAT) keeps track of the sectors that

store the various parts of a file

16-bit FAT (FAT16) uses 4 hexadecimal digits to number the sectors0000 thru FFFF

FAT is like a two-column spreadsheetColumn one numbers the sectorsColumn two contains the status of the sector

Bad sectors = FFF7 Good sectors = 0000

Format creates the FAT and then writes and reads from each sector to see if it is good


FAT Limitations16 bits can address only 64 K (216) sectors

Sector sizes limited to 512 bytes

64K X 512 bytes = 32 MB max size

Solution was clustering, allowing partition sizes up to 2 GB


Clustering Clustering combines a set of

contiguous sectors and treats them as a single unit

Called a cluster or file allocation unit Instead of numbering the sectors,

clusters were numberedAllowed partition sizes up to 2 GB

DOS, Windows 3.1, and the first version of Windows 95 all use FAT16 Newer OSs also support FAT16


How FAT WorksWindows looks for the first cluster marked 0000

(good & available for use)

If the file fits in that cluster, FFFF is put in the status column

If the file is larger than the cluster, Windows finds the next open clusterThat open cluster’s number is put in the first status

field to know where to linkProcess continues until the file is fully storedLast cluster’s status field is marked FFFF (end-of-

file)


Examples of FAT Storage1

2

3

4

0000 = Good FFF7 = Bad FFFF = End of File


FragmentationFragmentation occurs when files are spread

across drives (not contiguous)Individual files are broken into pieces that fit into

a sector or clusterThe pieces are stored on the hard drive but may

not be stored in contiguous clusters

Fragmentation slows down the system during hard drive reads and writes

Programs such as Disk Defragmenter or Speed Disk can be used to defragment files, folders, or both


Fragmented FileTakes longer for system to piece together

and can impact performance


Disk Defragmenter• Can defragment disk


FAT32 FAT32 was introduced with Windows 95

OSR2 (OEM Service Release 2)

Supports partitions up to 2 terabytes

Uses 32 bits to describe each cluster

Allows the use of small clusters

Can still become fragmented


CompTIA A+Technician

NTFS

IT Technician


NTFS File system of choice today

Six major improvementsand refinements1. Redundancy2. Security3. Compression4. Encryption5. Disk quotas6. Cluster sizing


NTFS ImprovementsNTFS structure

Uses an enhanced file allocation table called the Master File Table (MFT)NTFS keeps a backup copy in the middle of disk

SecurityProvides file and folder access controlUses Access Control List with permissionsIf you’re on the list, you’re granted the

specific permission


NTFS ImprovementsCompression

Allows files and folders to be compressed to save space

Encrypting file systemAllows files and folders to be encrypted and

unreadable to anyone without the key

Files and folders can beencrypted or compressed


NTFS ImprovementsDisk quotas

Can control how userscan use space

Set on a per-drive basis

Cluster sizesCan adjust cluster sizesRare to do so

NTFS supports 2 TBpartitions

Partitioning and Formatting Process


Bootable DisksAny removable media that has a bootable

OS installed

Floppy, CD-ROM, USB thumb drive

All Windows and Linux installation CDs are bootable

Common to create bootable media with tools added


Partitioning and FormattingWith Windows installation CD

During text portion of installCan create single partition



Allows you to set the size of the driveMinimum of 8 MB up to size of drive



Can format the drive with a file systemNTFS Quick—not as thoroughNTFS Regular—checks the drive



Can create multiple partitions


PATA Drive Letter Assignments

Primary partition of the1. Primary master drive2. Primary slave drive3. Secondary master drive4. Secondary slave drive

Then all logical drives in the extended partition of the1. Primary master drive2. Primary slave drive3. Secondary master drive4. Secondary slave drive

C:D:E:F:


SATA Drive Letter Assignments

Similar to PATA, but based on order set in CMOS1. Primary partition of the first drive2. Primary partition of the second drive3. Primary partition of the third drive4. Etc.

5. All logical drives in extended partition of first drive

6. All logical drives in extended partition of second drive

7. All logical drives in extended partition of third drive

8. Etc.


Disk ManagementGUI in Windows 2000 and XP

Used to manage partitionsPart of Computer Management Can be launched directly with diskmgmt.msc


Creating a New PartitionRight-click in unallocated space and choose New

Partition


New Partition Wizard


Disk ManagementCreating a partition in Windows

Pick partition type, size, and assign drive letter

< 4 GB can choose FAT, FAT32, or NTFS4 GB to 32 GB can choose FAT32 or NTFS> 32GB can choose only NTFS


Creating a Logical DriveOnce an extended partition is created, you may

create logical drives in it


Dynamic DisksDynamic disks are a new type of storage

available since Windows 2000 Not available in XP Home (available in XP Pro)Available in 2000 Server

and Server 2003Can convert basic to dynamicConverting dynamic to basic

causes all data to be lostRegular drives are known

as basic disksDynamic disks are divided into

volumes instead of partitions


Dynamic DisksSpanning volumes (one hard drive)

D: drive is spanned to include unallocated space

Effect is more space on D: volume

C:\ Volume 10 GB D:\ Volume 10 GB 30 GB unallocated space

C:\ Volume 10 GB D:\ Volume 10 GB 30 GB unallocated space

C:\ Volume 10 GB D:\ Volume 40 GB


Dynamic DisksExtended volumes (multiple hard drives)

Simple volume spanned across multiple disks

Effect is more space on D: volume


New disk—80 GB



Dynamic DisksSimple volume like a primary partitionStriped volume (RAID-0)Mirrored volume (RAID-1)Striped with parity (RAID-5)Desktop products (2000 Pro, XP Pro)

Support RAID 0

Server products (2000 & Server 2003)Support RAID 0, RAID 1, RAID 5


Mount PointsYour system partition drive (typically C:)

may be made dynamic Cannot be extended or spanned

Can create a mount point on C:Drive that functions like a folder mounted

into another drive

Provides additional storage on a hard drive by creating a folder that is another entire hard drive


Creating Mount PointsRight-click an unallocated space on a dynamic disk

and select New VolumeThe second screen in the wizard lets you create a mount

point instead of another drive letterWorks like folder

but appears as disk icon


Formatting a PartitionCan do in Windows Explorer

Can do in DiskManagement

Maintaining and Troubleshooting Hard Drives


ScanDisk and CHKDSKScanDisk and CHKDSK check for bad

clusters on hard drivesAlso checks for invalid filenames and tries to

fix themLooks for lost clusters or chains that do not

have a filename associated with them and deletes them

Checks the links between parent and child folders

Launched via Error-checking tools from Windows Explorer


Error-checkingCan check the drive

Can be set to fix errors automatically

Can scan for andrecover badsectors


DefragmentationDisk Defragmenter

Consider using regularly (monthly or weekly)Will slow down system while runningIf not done, system may slow down due to

fragmentationCan be scheduled


Disk CleanupAllows you to purge system

of unneeded files

Files in the Recycle Bin

Temporary Internet files

Downloaded program files

Temporary files


Troubleshooting Three broad categories:

1. Installation errors

2. Data corruption

3. Dying hard drives


Troubleshooting InstallationConnectivity

Hard drive errorNo fixed disks presentHDD controller failureNo boot device availableDrive not foundSolutions include

Checking the cables to make sure they connected properlyReseating the hard drive controller (if an expansion card)Use autodetection in CMOSCheck the jumper settingsSome EIDE drives are incompatible on the same controller


Troubleshooting InstallationCMOS

CMOS configuration mismatchNo boot device availableDrive not foundMissing OSSolutions

Always run autodetect in CMOSAlways select LBA


Troubleshooting InstallationPartitions

Failing to partition Invalid drive specification error

Making the wrong size or type of partition

FormatFailing to format

Drive is not accessible Invalid media type

“Trying to recover lost allocation unit” indicates the drive is dying


Troubleshooting CorruptionData corruption

Caused by many things such as power surges, accidental shutdowns, viruses, and more

Show up as File is missing or corrupt Download location information is damaged Unable to load file Cannot find command.com Error loading operating system Invalid boot.ini

Try running Error-checking utility


Troubleshooting CorruptionExtract/expand

Use to copy a specific file from an installation CD

Many files located inside a CAB (cabinet) file


Troubleshooting Installation

Corrupted data on bad sectors

The built-in error correction code (ECC) checks the drive for bad sectors

Disk checkers can be used to fix problems pertaining to corrupted data


Troubleshooting Dying HDDying hard drive

The following sounds indicate a drive about to dieContinuous high-pitched squealSeries of clacks, a short pause, and then more clacksContinuous grinding or rumbling

Boot drive issue would show up as “no boot device present”

Second drives simply do not show up


Third-Party Partition Tools Third-party partition tools allow you to

create, change, and delete partitions without destroying the data

PartitionMagic

VCOM’s Partition Commander

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