Secondary Storage

Chapter 8

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• 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 compress-ion and decompress-ion

Competencies (Page 1 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,

mass storage devices, and storage area networks

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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

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Secondary Storage Devices

• Provides permanent or nonvolatile storage

• Data and programs can be retained after the computer has been shut off

• Most desktop microcomputer systems have hard and optical disk drives

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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– External Hard Disks– Digital Versatile Discs

• Performance Enhancements

Hard Disks

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Materials that Cause a Head Crash

• Head crash is a disaster for a hard disk

8-7

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• Located inside system unit

• Designated as the C drive

• Advantages over other removable

media

– Capacity

– Access speed

Internal Hard Disk

8-8

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• Removable hard disks

• Used to complement internal

hard disk

• Capacities of 20 to 500 GB

External Hard Disks

8-9

PC Card Hard Disks

Hard-disk cartridge

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• Solid –state drives (SSDs)• Flash memory cards

– Widely used in notebook computers– Used to record MP3 music files

• USB Drives – Flash drives– Very compact– Capacity from 1 GB to 256 GB

Solid-State Storage

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• Hold over 50 gigabytes of data• Attributes

– Lands

– Pits

• Three types– Compact Disc (CD)

– Digital Versatile Disc (DVD)

– Hi-Def Disc

Optical Disks

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• 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

Making IT Work for YouIPods and Videos From The Internet

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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

Compact Disc

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• DVD stands for digital versatile disk or digital video disk

• DVD-ROM

• DVD+R and DVD-R

• DVD+RW, DVD-RW, and DVD-RAM

Digital Versatile Disks

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• 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

Digital Versatile Disc

8-15

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• 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

High-Definition Disc

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• Online storage services

• Floppy disks

• Magnetic tape

Other Types of Secondary Storage

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• 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

Magnetic Tape

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• 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

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• File servers

• Network attached storage (NAS)

• RAID systems

• Tape library

• Organizational online storage

Enterprise Storage Systems

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