Chapter 8
Secondary Storage
College of Computer and Information Science
Key Words & Terms
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access speed: 读写速度
Blu-Ray (BR): 蓝光
capacity: 容量
CD (compact disc): 紧凑格式盘
CD-R (CD-recordable): 可写CD（一次）
CD-ROM (compact disc-read only memory): 只读CD
CD-ROM jukebox: CD-ROM光盘库
CD-RW (compact disc rewritable): 可擦写CD（多次）
cylinder: 柱面
density: 密度
direct access: 直接读写
disk caching: 磁盘高速缓冲
DVD (digital versatile disc or digital video disc): 数字式通用盘
DVD player: DVD播放器
DVD-R or DVD+R (DVD recordable): 一次性刻录格式
DVD-RAM (DVD-random-access memory):可读写DVD
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Key Words & Terms
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DVD-ROM (digital versatile disc-read only memory): 只读DVD
DVD-RW or DVD+RW (DVD rewritable): 可擦写DVD
enterprise storage system: 大型存储系统
Erasable optical disk: 可擦写光盘
file compression: 文件压缩
file decompression: 文件解压
file server: 文件服务器
flash memory card: 闪存卡
floppy disk: 软盘
floppy disk cartridge: 大容量软盘
floppy disk drive (FDD): 软盘驱动器
hard disk: 硬盘
hard-disk cartridge: 移动式硬盘
hard-disk pack: 硬盘盘组
HD DVD (high-definition DVD): 高清DVD
head crash: 读写头损坏
hi def (high definition): 高清
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Key Words & Terms
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magnetic tape: 磁带
magnetic tape reel: 磁带卷
magnetic tape streamer: 流式磁带
mass storage: 海量存储
mass storage devices: 海量存储设备
media: 介质
optical disk: 光盘
optical disk drive: 光盘驱动器
organizational Internet storage: 高速网络存储
PC Card hard disk: PC卡式硬盘
pit: 光盘凹陷处
primary storage: 主存
RAID system: 冗余阵列盘系统
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Key Words & Terms
• redundant arrays of inexpensive disks (RAID): 冗余阵列
盘
• secondary storage: 辅助存储器
• secondary storage device: 辅助存储设备
• sector: 扇区
• sequential access: 顺序读写
• shutter: 磁盘读写口
• software engineer: 软件工程师
• solid-state storage: 固态存储器
• storage devices: 存储设备
• tape cartridge: 磁带盒
• tape library：磁带库
• track: 磁道
• USB drive: USB驱动器
• write-protection notch: 写保护口
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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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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
• Describe solid-state storage, Internet drives, and
magnetic tape
• Discuss mass storage and mass storage devices
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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.
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Storage
• Primary storage
• Secondary storage
– Volatile storage
– Temporary
storage
– Nonvolatile storage
– Permanent storage
• Secondary storage
characteristics
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Media
Capacity
Storage devices
Access speed
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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
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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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Traditional Floppy Disk
• Most common type is 2HD “two-sided, highdensity”
• Attributes
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Shutter
Labels
Write-protection notch
Tracks
Sectors
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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
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Hard Disks
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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
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Materials that Cause a Head
Crash
• Head crash is a disaster for a hard disk
Return
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Internal Hard Disk
• Located inside system unit
• Designated as the C drive
• Advantages over floppies
– Capacity
– Access speed
Return
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Hard-Disk Cartridges
• Removable hard disks
• Used to complement
internal hard disk
Hard-disk cartridge
• Capacities of 20 to 100 GB
• Iomega is one of the most
widely used
PC Card Hard Disks
Return
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Hard-Disk Packs
• Removable hard
disk
• Massive storage
capacity
• Common in
mainframes
• Are utilized by
banks and credit
card companies
Return
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Performance Enhancements
• Disk caching
• Redundant arrays of
inexpensive disks (RAID)
• File compression
and decompression
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Optical Disks
• Hold over 50 gigabytes of data
• Attributes
– Lands
– Pits
• Three types
– Compact Disc (CD)
– Digital Versatile Disc (DVD)
– Hi-Def Disc
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Compact Disc
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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
Return
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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
Return
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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
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Other Types of Secondary
Storage
• Solid-state storage
• Internet hard drives
• Magnetic tape
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Ipods and 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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Solid-State Storage
• Flash memory cards
– Widely used in notebook computers
– Used to record MP3 music files
• USB drives
Flash memory card
– Key ring flash memory
devices or flash drives
– Connects to a USB port
Key ring flash memory
Return
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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
Return
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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
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Mass Storage Devices
• Mass storage refers to the tremendous
amount of secondary storage required by
large organizations
• Mass storage devices are specialized highcapacity secondary storage devices
• Enterprise storage system
promotes efficient and safe
use of data across networks
within organizations
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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.
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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.
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End of Chapter 8
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