A+ Guide to Managing and Maintaining Your PCFifth Edition

Chapter 9

Optimizing and Protecting Hard Drives

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Hands-on Project: Install a Slave Drive

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Managing Hard Drives Disk defragmentation ScanDisk Disk Cleanup Disk compression Disk caching Disk cloning Making backups

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Fragmentation

Desirable

A file is placed in contiguous clusters

A file is placed in discrete clusters

Fragmented

Slow down access time Complicate recovery of a corrupted file

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Windows Defragmenter

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Hands-on Project: Defragmenter

pp. 360

Start->All Programs->Accessories->System. Tools->Disk Defragmenter

Do a fragmentation analysis

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Cross-Linked and Lost Clusters

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ScanDisk Repairs cross-linked and lost clusters

Checks FAT for problems with long filenames and the directory tree

Scans the disk for bad sectors

Repairs problems with structure of a hard drive that has been compressed using Windows DriveSpace or DoubleSpace

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ScanDisk

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Hands-on Project: ScanDisk

pp. 362 Windows Exploer->right –click the drive->

Properties->Tools tab->Check Now under Error-checking->check the two check-boxes

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Clean Up Disks

Delete temporary files to free up space

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Disk Cleanup

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Hands-on Project

pp. 364 Windows Explorer-> right-click the drive-

>Properties->General tab->Disk Cleanup

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Disk Compression

Save hard drive space

May loose data

May result in longer disk access time

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Hand-on Project: Compress an NTFS Drive Windows XP/2000 pp. 366

Explorer->Properties->General->Check “Compress drive to save disk space”

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Hands-on Project: Compress a File/Folder in Windows XP/2000 pp. 366

Explorer->Properties->General->Advanced->Check “compress contents to save disk space”

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Disk Cache

Temporary storage area in RAM for data being read from or written to a hard drive

Speeds up access time to the drive

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Disk Caching

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Hardware Cache

Built in the hard drive controllers

The BIOS on the controller contains the cache program

RAM chips on the controller hold the cached data

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Software Cache

A software that is loaded into the memory during boot-up

Uses system RAM to hold the cached data

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Hardware Cache vs. Software Cache Advantages: does not use system RAM

Disadvantages

Slower

Impractical to update

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Disk Caching in Windows

Windows NT/2000/XP: automated disk caching

Windows 9x: VCACHE

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Hands-on Project: Enable Disk Cache pp. 367 and Figure 9-9

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Backups

A backup is an extra copy of a file The backup can be used to recover the original

file if it is damaged

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Backup Types

Full backups: back up all data from hard drive

Incremental backups: back up only files that have changed or been created since last backup

Differential backups: back up files that have changed or been created since the last full backup

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Example Backup Methods

Perform a full backup every Friday, and incremental backups Monday through Thursday

Perform a full backup every Friday, and differential backups Monday through Thursday

Discussion: advantages and disadvantages of each method?

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Hands-on Project: Windows 2000/XP Backup pp. 375 - 376

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Disk Cloning (Disk Imaging)

Replicates a hard drive to multiple computers

Software for disk cloning

Drive Image by PowerQuest

ImageCast by Innovative Software

Norton Ghost by Symantec Corp

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Computer Infestations

Any unwanted program transmitted to a computer without the knowledge of the user

Are designed to do varying degrees of damage to data and software

Do not damage hardware The hard drive may appear to be physically

damaged when the boot sector information is destroyed

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Computer InfestationsVirus Needs a host program

Infected program must be executed for a virus to run replicates by attaching to other programs Has an incubation period (does not do damage

immediately)

Worm Spreads copies of itself without a host program Does damage by overloading the network or the system Best defense is a firewall

Trojan horse Substitutes itself for a legitimate program Does not need a host program to work Most cannot replicate

Logic bomb Dormant code added to software; triggered at a predetermined time or by a predetermined event

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Virus Types

Boot sector viruses The Master Boot Record program The OS Boot Record program

File viruses Executables (.exe, .com, or .sys) Word files containing macros (Macro viruses)

Multipartite viruses

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How a Virus Replicates

Non-memory-resident virus

Memory-resident virus

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Anti-virus Software

Looks for distinguishing characteristics (virus signatures)

Looks for a program that can replicate itself Monitors the difference between a program’s

file sizes

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Virus Cloaking Techniques

Polymorphic viruses – changes its distinguishing characteristics as it replicates

Encrypting viruses – transform itself into a nonreplicating program

Stealth viruses Alters OS to mask the size of the host file Resets the host file before it is opened

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How a Worm Gets into Your Computer

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Virus Hoaxes

E-mail warnings about a nonexistent virus

Overload network traffic

Check Web sites that specialize in debunking virus hoaxes

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Protecting Against Computer Infestations Do not run programs or email attachments unless you

are sure that they are safe

Implement a firewall to protect ports

Open only necessary ports to specific IP addresses

Keep Windows current with updates and patches

Install and run an anti-virus software

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Damaged Partition Table Messages - Invalid drive or drive specification

Solutions

A> Fdisk /Mbr

Recovery Console: fixmbr

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Damaged OS Boot Record Messages

Invalid media type

Non-DOS disk

Unable to read from Drive C

Solutions

Recover from backup

Third-party software

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Damaged FAT, Root Directory, or Bad Sectors Messages

Sector not found reading drive C

Bad sector

Solutions

Scandisk

Third-party recovery software

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Damaged System Files Messages

Non system disk or disk error

Invalid system disk

Solutions

Copy systems to the drive by sys C: