Chapter 004 - (Lecture) - Disk Management 007

Hard Disks Overview

  • A hard disk drive (HDD) stores files, operating systems, and applications.

  • Performance factors:

    • Storage Capacity: Amount of data it can hold (larger drives store more files).

    • Data Transfer Speed: Faster read/write speeds lead to quicker load times for applications and games.

  • Major storage technologies:

    • Magnetic Hard Drives (HDDs)

    • Solid-State Drives (SSDs)

    • Non-Volatile Memory Express (NVMe)

Magnetic Storage

Definition

  • Magnetic storage devices store data using magnetic media, such as HDDs and magnetic tapes.

  • Data is represented as binary (0s and 1s) by altering the magnetic polarity of storage medium.

Hard Disk Drives (HDDs)

  • Comprise spinning disks (platters) coated with magnetized metal grains.

  • Speed: Platters rotate at 5400 to 15,000 RPM.

  • Average data transfer rate: 80 to 160 MB/s.

Data Writing and Reading Process

  • Data Writing:

    • A write head changes magnetic orientation of particles to represent binary data.

  • Data Reading:

    • A read head detects magnetic polarity to determine binary representation.

Disadvantages of Magnetic Storage

  • Slower Data Transfer: Due to reliance on moving parts leading to higher access times.

  • Vulnerability to Damage: Physical shocks can harm the read/write head and platters.

  • Size and Weight: Generally bulkier and heavier compared to SSDs.

  • Higher Power Consumption: Requires more energy for spinning disks.

  • Noise Generation: Moving parts produce noise during operation.

Tape Storage

Definition

  • Magnetic tape is a plastic strip with a magnetic coating for data storage; commonly used for backups.

  • Capacity: Ranges from 1 to 16 terabytes (up to 580 TB for specific IBM models).

  • Cost-efficient: E.g., 10TB tape averages $40.

  • Longevity: Can store data for up to 30 years.

  • Disadvantages include slow copying speeds and bulk data access.

Solid-State Drives (SSD)

Definition

  • SSDs use flash memory to store data, lacking moving parts which makes them faster and more reliable than HDDs.

  • Average data transfer rate: 2000 to 3500 MB/s.

Flash Memory

  • Stores data electronically using cells to hold electrical charges representing binary data.

  • New generation chips can store multiple bits per cell ( Multi-Level Cells).

Advantages and Disadvantages

  • Advantages:

    • Access data uniformly and quickly from any cell.

    • Speed benefits with higher data transfer rates and no mechanical delay.

  • Disadvantages:

    • Limited write cycles lead to a shorter lifespan.

    • Data retention may be lower compared to HDDs if left unpowered.

NVMe Technology

Definition

  • Non-Volatile Memory Express is a modern storage interface maximizing performance over PCIe bus.

  • Allows for parallel data access, significantly improving performance over traditional SATA SSDs.

Key Differences from SATA SSDs

  • NVMe utilizes multiple I/O queues for simultaneous processing, enhancing data access speed compared to the sequential nature of SATA connections.

File Systems

Purpose

  • Organizes, stores, retrieves, and manages data on drives (HDDs, SSDs).

  • Defines data structure and access methods essential for proper file management.

Key Functions

  • File Organization: Arranges files in a hierarchical structure.

  • Storage Management: Allocates physical storage on the disk.

  • File Access: Mechanisms for reading, writing, or deleting files.

  • Security Features: Ensures protection against unauthorized access.

  • Data Integrity: Holds backup mechanisms to protect against corruption.

Common File Systems

  • NTFS: Modern Windows file system.

  • FAT32: Older system, compatible across devices.

  • exFAT: Optimized for large file support on external storage.

  • APFS: Newer system for Apple devices optimized for SSDs.

Partitioning and Formatting

Importance

  • Windows requires partitions to access and manage drives effectively.

  • Partitions organize data and maintain system integrity during OS updates or installations.

Concept of Partitioning

  • Splits the hard disk into independent sections to manage data securely.

  • Users can create separate partitions for OS and personal files.

Formatting Process

  • Prepares partitions with a file system for use; this process erases existing data.