Secondary Storage Overview and Key Concepts

Learning Objectives

  • Distinguish between Primary and Secondary Storage: Understand the differences in volatility and usage between these two storage types.
  • Important Characteristics of Secondary Storage: Identify key characteristics including media, capacity, storage devices, and access speed.
  • Hard Disk Components: Learn about platters, tracks, sectors, cylinders, and potential head crashes.
  • Internal vs External Hard Drives: Compare the features, advantages, and uses of internal and external hard drives.
  • Performance Enhancements: Understand techniques including disk caching, RAID configuration, file compression, and decompression.
  • Optical Storage: Define and discuss compact discs (CDs), digital versatile discs (DVDs), and Blu-ray discs.
  • Solid State Storage: Familiarize with solid state drives (SSDs), flash memory cards, and USB drives.
  • Cloud Storage: Learn what cloud storage is and the services it provides.
  • Mass Storage and related Systems: Describe mass storage solutions including enterprise storage systems and storage area networks (SANs).

Introduction to Data Storage

  • Transformation from basic text and numeric storage to varied forms including digital music, photos, and videos.
  • Need for secondary storage devices to handle large capacities due to file size increase.

Primary vs Secondary Storage

  • Primary Storage:
    • Volatile: Loses stored data when power is lost (e.g., RAM).
    • Temporary: Only retains information while the system is on.
  • Secondary Storage:
    • Nonvolatile: Retains data without power (e.g., hard disks).
    • Permanent: Stores information long-term for future access.

Characteristics of Secondary Storage

  • Media: The physical aspect that holds data and programs.
  • Capacity: The total amount of data that can be stored.
  • Storage Devices: The hardware used to read/write data from/to storage media.
  • Access Speed: Time required to retrieve data from storage devices.

Hard Disks

  • Store files by altering magnetic charges to represent binary data (1s and 0s).
  • Use stacked rigid metallic platters and organize files using tracks, sectors, and cylinders.
  • Types:
    • Internal Hard Drives: Installed inside a computer.
    • External Hard Drives: Portable drives connected via USB or other interfaces.
    • Network Drives: Shared drives on a network system.

Performance Enhancement Techniques

  • Disk Caching: Anticipates and keeps frequently accessed data in memory.
  • RAID (Redundant Array of Independent Disks): Combines multiple drives for redundancy and performance.
  • File Compression: Reduces file size for more efficient storage.
  • File Decompression: Restores compressed files to their original size.

Optical Disks

  • Capable of holding over 128 GB of data.
  • Use laser light to read/write data with pits (bumps) representing 0s and 1s.
  • Types:
    • CDs: 700 MB capacity (standard optical disc).
    • DVDs: 4.7 GB (current standard).
    • Blu-ray: 50 GB (high-definition).
    • UHD Blu-ray: 100 GB (for 4K video).
  • Access Types:
    • ROM: Read-only, cannot be altered.
    • R: Recordable, can be written once.
    • RW or RAM: Rewritable, can be erased and rewritten.

Cloud Storage

  • Uses internet-based storage solutions provided by services:
    • Dropbox, Google Drive, Microsoft OneDrive, Amazon Drive, Apple iCloud.
  • Advantages: Easy sharing, scalable, accessible from anywhere.
  • Disadvantages: Dependency on internet connection, potential security concerns.

Mass Storage Devices

  • Required for organizations with significant storage needs.
  • Types of Devices:
    • File Servers: Store and manage files across a network.
    • RAID Systems: Enhance performance and safety of data storage.
    • NAS (Network Attached Storage): Dedicated storage unit connected to the network.
    • Cloud Storage Systems: Organizational solutions for data access and backup.

Storage Area Network (SAN)

  • Architecture facilitating connectivity of remote storage devices.
  • Allows users to access large volumes of data securely despite physical distance.

Careers in IT

  • Disaster Recovery Specialists: Focus on recovery of systems post-disaster; requires a degree in computer science or related fields.
  • Skills needed: Networking, security, database administration, and communication under stress.

Future of Storage

  • Innovations may include using heat, lasers, or even DNA for data storage.
  • Ongoing research aims to increase storage capacity without increasing physical size.

Open-Ended Questions for Review

  • Compare and contrast primary and secondary storage. Discuss characteristics of secondary storage.
  • Explore the mechanics of hard disks and enhancements in performance.
  • Discuss the significance and types of solid-state and optical storage.
  • Explain cloud computing and its advantages.
  • Describe enterprise mass storage solutions and systems like SAN.