1. Chapter 8
Secondary Storage

2. Competencies (Page 1 of 2)
Distinguish between primary and secondary storage
Describe the traditional floppy disk and compare it to high capacity floppy disks
Compare internal hard disks, hard-disk cartridges, and hard-disk packs
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3. Competencies (Page 2 of 2)
Describe ways to improve hard-disk operations, including disk caching, redundant arrays of inexpensive disks, and data compression and decompression
Discuss the different types of optical disks; mass storage
Describe solid-state storage, Internet drives, and magnetic tape
Discuss mass storage and mass storage devices
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4. Secondary Storage Devices
Most desktop microcomputer systems have floppy disks, hard disks, and optical disk drives
Are used to save, back up, and transport data files and programs
Floppy disk – inexpensive and removable
Optical disks – large storage capacity (Key Term)
Hard disk – large storage capacity and fast retrieval times
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5. Storage RAM Primary storage Secondary 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 (Key Term) – 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 (Key Term) – measures the amount of time required by the storage device to retrieve data and programs
Writing (Key Term) – process of saving information to the secondary storage device
RAM
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6. Floppy Disks Portable or removable storage media
Typically used to store and transfer small word processing, spreadsheet, and other types of files
Floppy disk drives (FDD)
Store data and programs
Retrieves data by reading electromagnetic charges
Also called flexible disks and floppies
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7. Traditional Floppy Disk
Most common type is 2HD “two-sided, high-density”
Attributes
Shutter
Labels
Write-protection notch
Tracks
Sectors
Floppy disks are removable storage media. Today’s standard is 1.44 MB 3½-inch disk (Key Term). Data recorded in rings called called tracks; tracks divided into wedge-shaped sections called sectors
Most disks (Key Term) manufactured currently preformatted w/tracks and sectors
While called floppy, actually pieces of flat Mylar rotating within a hard plastic jacket
The bits of data are represented by the presence or absence of magnetic charges
Storage capacities range from 360 KB to 1.44 MB
Write-protect notch or window to prevent inadvertent erasure or write-over
Density (Key Term) refers to how tightly the bits can be packed next to one another; common density is 2HD
A shutter on the disk slides to the side to expose the recording surface
Labels provide an area to write or document the contents of the disk
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8. High Capacity Floppy Disks
Known as a floppy-disk cartridge
Require special disk drives
Most widely used is the Zip disk
100 MB, 250 MB or 750 MB capacity
Used to store multimedia, database, large text, and spreadsheet files
Floppy-disk cartridge can also be referred to as a high-capacity disk (Key Term)
Zip disks – usually manufactured by Iomega; 100 MB, 250 MB, or 750 MB worth of storage; requires own drive
HiDF disks – usually manufactured by Sony Corp; 200 MB or 750 MB capacity
Biggest advantages: can use HiDF disk in floppy drive; popular with notebooks
Super disks – usually manufactured by Imation; 120 MB or 240 MB capacity; SuperDisk disk drives can use standard floppy disks
Zip disks – 100 MB, 250 MB or 750 MB
HiFD disks MB or 720MB
SuperDisks – 120 MB or 240 MB
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9. 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
Hard-disk cartridge
Hard-disk pack
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
An internal hard disk is also known as a fixed disk (Key Term)
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10. 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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11. Internal Hard Disk Located inside system unit Known as a fixed disk
Designated as the C drive
Advantages over floppies
Capacity
Access speed
Located inside the system unit; also known as fixed disk
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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12. Hard-Disk Cartridges Removable hard disks
Used to complement internal hard disk
Capacities of 20 to 100 GB
Iomega is one of the most widely used
Hard-disk cartridge
PC Card Hard Disks
Capacity limited only by number of cartridges; used to complement internal hard disk.
Popular Vendor: Peerless disks from Iomega
PC Card hard disk (Key Term) available for notebooks with a capacity of up to 5 GB
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13. Hard-Disk Packs Removable hard disk Massive storage capacity
Common in mainframes
Are utilized by banks and credit card companies
Massive storage capacity
Common in mainframe systems
Composed of a larger number of platters, resembling a stack of record albums
Most platters offer read-write surfaces on top and bottom
Access time – time between the computer’s request for data from secondary storage and the completion of the data transfer; usually access time is faster with this type of secondary storage
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14. Performance Enhancements
Disk caching
Redundant arrays of inexpensive disks (RAID)
File compression and decompression
RAID storage device
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 PKZip are well-known programs, and you can also use utility programs in Windows XP
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15. Optical Disks Hold over 17 gigabytes of data Attributes Three types
Lands
Pits
Rotational speed
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 17 gigabytes of data)
Optical discs are read by an optical disc drive (Key Term)
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
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16. 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)
Known as CD burners (Key Term)
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
Most newer CD-ROMS are multiread, (Key Term) or able to read both CD-R and CD-RW discs
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17. 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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18. Hi-Def 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 30 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
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19. Other Types of Secondary Storage
Solid-state storage
Internet hard drives
Magnetic tape
Solid-state storage
No moving parts
Reliable, but expensive
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
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20. Solid-State Storage Flash memory cards Key chain hard drives
Widely used in notebook computers
Used to record MP3 music files
Key chain hard drives
Key chain flash memory devices or flash drives
Connects to a USB port
Flash memory cards
Key chain hard drives have recently been introduced
Very compact
Worn as a necklace or on a key ring
Connect to a USB port
Predicted that they will replace the floppy disk for transporting data
Capacities up to 1 GB
Key chain flash memory
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21. 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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22. 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
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23. Music From The Internet
The Internet can be used as a medium to locate and play music
A user can create compact discs, or transfer music to a portable player
Requirements
Software
Hardware
Internet
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24. 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
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25. 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 $50K to $85K
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26. A Look to the Future Your Entire Life Recorded on 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?
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27. Discussion Questions (Page 1 of 2)
Discuss the traditional and high-capacity floppy 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 hi def? 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
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28. Discussion Questions (Page 2 of 2)
Discuss solid-state storage, 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
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