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Secondary StorageChapter 4

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Overview

Discuss Secondary Storage Characteristics

Describe Hard Drive Parts

Compare Internal and External Hard Drives

Discuss Performance Enhancements

Define Optical Storage

Define Solid-state StorageDefine Cloud Storage and Cloud Services

Discuss Mass Storage

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Storage

Primary Storage

Volatile

Temporary

e.g., RAM

Secondary Storage

Nonvolatile

Permanent

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Storage

Secondary Storage Characteristics

Media

Physical Material that Holds Data and Programs

Devices

Read or Write to or from Media

Access Speed

Time Required to Read Data and Programs

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Storage

Secondary Storage Characteristics

Capacity

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Hard Disks

Main Storage for System Unit

Stores Data Using Magnetic Charges

Positive / Negative Charges Represent Bits

Sealed in Airtight Case

Media

Rigid Metallic Platter

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Hard Disks

Platter

Tracks

Rings of Concentric Circles

Sector

Wedge-shaped Sections

Cylinder

Vertically Passes Through Stack of Platters

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Hard Disks

Head Crash

Spinning Creates Air Cushion

Floats Read / Write Head Above Platter

Crash

Head Contacts Surface

Clearance = 0.000001” 

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Hard Disks

InternalOS

Major Applications

External

Connect Via USB

Protect or Secure Sensitive Information

Back Up Internal Hard Disk Contents

Providing Additional Hard Disk Capacity

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Hard Disks

Performance EnhancementsDisk Caching

Performed During Idle Processing Time

Frequently Used Data Read into RAM Cache

RAID (Redundant Arrays of Independent Disks)

Several Hard Disks Treated as a Large-capacity Drive

Fast Access Speed

High Reliability

File Compression

Reduce Space Required to Store Data and Programs

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Optical Discs

Laser and Reflected Light Represent Data

Mechanics

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Optical Discs

CD (Compact Disc)

DVD (Digital Video Disc)

BD (Blu-ray Disc)

Formats

-ROM

-R

-RW, -RE

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Optical Discs

Storage

CD

700MB

DVD / BD

Two Sides Can be Used

Two Layers of Pits Can be Used

Lower Layer is Semitransparent

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Solid-State Storage

Solid –state Drives (SSDs)

No Moving Parts, Fast, Durable

Flash Memory Cards

USB Drives (or Flash Drives)

Connect to USB Port

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Cloud Computing

Internet ServiceProvides Storage to Computer Users

Benefits

Access Files From Any Computer

Allow Others to Access Their Files

Store Offsite Backups

Google Apps

Dropbox

Office 365

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Mass Storage Devices

Enterprise Storage System

File Servers

Networked Attached Storage (NAS)

RAID Systems

Tape Libraries

Organizational Cloud Storage

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Mass Storage Devices

Storage Area Network (SAN)

Architecture to Link to Remote Storage

User’s Computer Provides File System 

SAN Provides Disk Space

Requires

High-speed Network

Special File System

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