a+ guide to managing and maintaining your pc fifth edition chapter 9 optimizing and protecting hard...
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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: