1. Chapter 8
Secondary Storage

2. Competencies (Page 1 of 2)
Distinguish between primary and secondary storage
Compare internal and external hard disks
Describe ways to improve hard-disk operations, including disk caching, redundant arrays of inexpensive disks, and data compression and decompression
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3. Competencies (Page 2 of 2)
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Competencies (Page 2 of 2)
Discuss solid-state storage devices including flash memory and USB drives
Discuss the different types of optical disks
Describe Internet drives, floppy disks, and magnetic tape
Discuss mass storage, floppy disks, and mass storage devices
Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved.

4. Introduction
Data storage has expanded from text and numeric files to include digital music files, photographic files, video files, and much more. These new types of files require secondary storage devices with much greater capacity than floppy disks. In this chapter, you will learn about the many types of secondary storage devices including their capabilities and limitations.
Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved.

5. Storage RAM Primary storage Secondary storage
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Storage
Primary storage
Volatile storage
Temporary storage
Secondary storage
Nonvolatile storage
Permanent storage
Secondary storage characteristics
Media
Capacity
Storage devices
Access speed
Secondary storage permanently saves information for future use; to share information with others; to modify at later date
Secondary storage is nonvolatile – stores programs and data as opposed to temporary storage (RAM)
Characteristics include:
Media or medium – actual physical materials that holds the data and programs
Capacity – measures how much a particular storage medium can hold
Storage devices – hardware that reads data and programs from storage media (most also write to storage media)
Access speed or access time – measures the amount of time required by the storage device to retrieve data and programs
Writing– process of saving information to the secondary storage device
Reading – process of accessing information from secondary storage
RAM
Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved.

6. Secondary Storage Devices
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Secondary Storage Devices
Most desktop microcomputer systems have hard disks and optical disk drives
Are used to save, back up, and transport data files and programs
Optical disks – large storage capacity (Key Term)
Hard disk – large storage capacity and fast retrieval times

7. Hard Disks Use thicker, metallic platters for storage
Faster than a floppy diskette
Large capacity
Sensitive instruments
There are three types of hard disks:
Internal Hard Disk
External Hard Disks
Digital Versatile Discs
Performance Enhancements
Composed of metallic rather than plastic disks
Platters – rigid metallic, stacked one on top of another
A cylinder (Key Term) runs through each track of a stack of platters
Fast information storage and retrieval
Read-write head is inch above surface
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8. Materials that Cause a Head Crash
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Materials that Cause a Head Crash
Head crash is a disaster for a hard disk
Head crashes occur when the read-write head contacts with the disk surface or with particles on the disk's surface
Head crashes are now rare
A smoke particle, human hair, or fingerprint could cause a head crash
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9. Internal Hard Disk Located inside system unit
Designated as the C drive
Advantages over other removable media
Capacity
Access speed
Located inside the system unit
Used for storing the operating system, other programs, and large data files
You should perform routine maintenance and periodically backup all important files
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Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved.

10. External Hard Disks Removable hard disks
Used to complement internal hard disk
Capacities of 20 to 500 GB
Hard-disk cartridge
Capacity limited only by number of cartridges; used to complement internal hard disk.
PC Card hard disk (Key Term) available for notebooks with a capacity of up to 5 GB
PC Card Hard Disks
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Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved.

11. Digital Versatile Disks
DVD stands for digital versatile disk or digital video disk
DVD-ROM
DVD+R and DVD-R
DVD+RW, DVD-RW, and DVD-RAM
Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved.

12. Performance Enhancements
Disk caching
Redundant arrays of inexpensive disks (RAID)
File compression and decompression
Disk caching
Uses hardware and software to anticipate data needs; performs function similar to RAM caching; improves processing by acting as a temporary high-speed holding area between a secondary storage device (Key Term) and the CPU
Frequently used data is stored in memory; when needed, the access time is much faster
Redundant arrays of inexpensive disks (RAID)
Groups of low cost hard-disk drives grouped together using networks and special software
Performs as a single large-capacity disk; but faster than a single disk of comparable size
Often used by Internet servers and large organizations
File compression and decompression
Increase storage capacity
Reduce space required for storage; reduce up to ¼ of original size
WinZip and UltimateZip are well-known programs, and you can also use utility programs in Windows XP
Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved.

13. Optical Disks Hold over 50 gigabytes of data Attributes Three types
Lands
Pits
Three types
Compact Disc (CD)
Digital Versatile Disc (DVD)
Hi-Def Disc
Use laser technology. CD (Key Term) and DVD (Key Term) are optical disk formats.
Compact, high capacity form of permanent storage (up to 50 gigabytes of data)
Optical discs are read by an optical disc drive
Laser beam writes by creating a pattern of pits (holes) and lands (flat areas) to encode data bits
Laser beams reflect off the pits and lands to read the data
Rotational speed determines how fast data can be transferred from the CD
Optical disks come in many different sizes
Most common is 4 ¾ inches
Stored in a protective case called jewel boxes
Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved.

14. Compact Disc Optical format From 650 MB to 1 GB capacity
Rotation speeds vary
Three basic types
Read only: CD-ROM
Write once: CD-R
Rewriteable: CD-RW
CD stands for compact disc
Standard on most computers; can store from 650 MB up to 1 GB
Speed determines how fast data can be transferred
Read only: CD-ROM
Commercial music CD
Read only means it cannot be written on or erased
Used to distribute large databases and references
Write once: CD-R (CD-recordable)
Used to archive data or to record music downloaded from the Internet
Rewriteable: CD-RW
Known as erasable optical disks (Key Term)
Can be changed
Used to create and edit multimedia presentations
Ideal for use as permanent data archives for essential company information
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Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved.

15. Digital Versatile Disc
Digital Versatile Disc or Digital Video Disc (DVD)
Similar to CDs, but can store more data
Three basic types
Read only: DVD-ROM
Write once: DVD+R; DVD-R
Rewritable: DVD+RW; DVD-RW; DVD-RAM
DVD-ROM
Known as DVD players (Key Term)
Used for videos
DVD-R and DVD+R
Two competing write once formats
Write once format
Used to create permanent archives for large amounts of data and to record videos
DVD-RAM or DVD-RW – rewritable version
DVD-RW
DVD+RW
DVD-RAM
Each format has a unique way of storing data; older DVD players can’t read all formats but the new DVD players can
Rapidly replacing the CD rewritable drives
Use to store video from camcorders and developing large multimedia presentations that include extensive graphics and video
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Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved.

16. High-Definition Disc Next generation of optical disc
Far greater capacity than DVDs
Three basic types
Read only
Write once
Rewriteable
Two competing hi def formats
HD DVD
Blu-Ray
HD DVD stands for high definition DVD
Capacity of 15 to 45 gigabytes
Advantage is that current manufacturing plants producing standard DVD discs can be easily converted to mass produce HD DVD discs
Blu-Ray, also known as BDs
Have a capacity of 25 to 50 gigabytes
Cannot be easily manufactured in existing DVD disc manufacturing plants
The two formats appear that they will not be compatible with each other
Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved.

17. Other Types of Secondary Storage
Solid-state storage
Internet hard drives
Magnetic tape
Solid-state storage
No moving parts
Reliable, but expensive
Requires less power
Internet hard drives (Key Term)
Low cost
Flexibility to access information from any location using the Internet
Slower access speed
Magnetic tape
Slower sequential access (Key Term)
Stores data and programs
Used for making backups of data
Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved.

18. Ipods and Videos From The Internet
The Internet can be used as a medium to locate and play music and videos
A user can create compact discs, or transfer music to a portable player
Requirements
Software
Hardware
Internet
Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved.

19. Solid-State Storage Flash memory cards
Widely used in notebook computers
Used to record MP3 music files
Flash memory card
Flash memory cards are one type of solid state device.
Return
Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved.

20. Internet Hard Drives Known as i-drive or online storage
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Internet Hard Drives
Known as i-drive or online storage
Low cost and can access information from any location using the Internet
Oriented to either businesses or individuals
These are Web sites that provide storage space
Not used for storing highly personalized or sensitive information
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21. Magnetic Tape External storage Provides sequential access
Information stored in sequence
Slower than disks which provide direct access
Magnetic tape streamers or tape cartridges used by both mainframes and microcomputers
Sequential access because they have to be fast forwarded or rewound before a specific location can be reached
A common sequential access method of permanent storage method
Common form of data backup in companies with larger computer systems; magnetic disk offer fast, direct access to data programs
Two forms of tape storage
Magnetic tape streamers
Backup tape cartridge units used with microcomputer systems
Capacities range from 120 MB to 5 GB
At one time, mainframe computers used magnetic tape reels (Key Term) exclusively
Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved.

22. Mass Storage Devices
Mass storage refers to the tremendous amount of secondary storage required by large organizations
Mass storage devices are specialized high-capacity secondary storage devices
Enterprise storage system
promotes efficient and safe
use of data across networks
within organizations
Mass storage devices that support enterprise storage systems are
File servers (Key Term) – dedicated computer with very large storage capacities that provide user access to fast storage and retrieval of data
RAID systems (Key Term) – larger versions of the specialized devices discussed earlier in this chapter that enhance organizational security by constantly making backup copies of files moving across the organization’s networks
Tape library (Key Term) – device that provides automatic access to data archived on a large collection or library of tapes
DVD-ROM and CD-ROM jukeboxes (Key Term) – provide automatic access to a large collection or library of optical disks
Organizational Internet Storage (Key Term) – high-speed Internet connection to a dedicated remote organizational Internet drive site
Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved.

23. Careers In IT
Software engineers analyze users’ needs and create application software
General employer requirements
Bachelors degree in computer science
Extensive knowledge of computers
and technology
Good communication and analytical skills
Software engineers can expect to
earn an annual salary of $63,000 to $98,500
Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved.

24. A Look to the Future Your Entire Life Recorded on a Single Disk
Future secondary storage disks could eventually store one terabyte
Experiments with three dimensional storing
Video of an entire life
Technology is being used to
rapidly scan photos and videos
Are there downsides?
Could your personal video log be used to incriminate you in a court of law?
Could someone else’s video log be an invasion of your right to privacy?
Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved.

25. Discussion Questions (Page 1 of 2)
Compare solid-state storage and hard disks.
What are the three types of hard disks? Describe three ways to improve hard disk performance.
What are the two most common optical disk formats? What is Blu-Ray? Describe the basic types for each format.
Have students turn to the end of Chapter 8 in their textbooks to view the same “Open-Ended” questions/statements
Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved.

26. Discussion Questions (Page 2 of 2)
Discuss Internet hard drives and magnetic tape. What are the advantages and disadvantages of each?
Discuss mass storage, enterprise storage systems, and mass storage devices.
Have students turn to the end of Chapter 8 in their textbooks to view the same “Open-Ended” questions/statements
Copyright © 2010 by The McGraw-Hill Companies, Inc. All rights reserved.