JH

Chapter 2 Notes

Exam Objectives (Domain 3.x)

  • 3.3 Select & Install Storage Devices

    • Conventional hard-disk drives (HDD): Data stored magnetically on platters. Rotational speeds directly impact performance and average latency:

      • 5400\ rpm (common for external/archive drives)

      • 7200\ rpm (standard desktop performance)

      • 10000\ rpm (high-performance desktops/entry servers)

      • 15000\ rpm (enterprise/server drives requiring fastest I/O)

    • Form-factors:

      • 3.5\,\text{in}\, (standard for desktop PCs and most servers)

      • 2.5\,\text{in}\, (laptops, some small form-factor devices, and server SSDs)

    • Solid-state drives (SSD): Utilize NAND flash memory for data storage; no moving parts.

    • Communication interfaces:

      • Serial ATA (SATA): A serial link interface for HDDs and SSDs. Common versions include:

      • SATA I: 1.5\,\text{Gb/s}\, (150\,\text{MB/s}) theoretical maximum

      • SATA II: 3\,\text{Gb/s}\, (300\,\text{MB/s}) theoretical maximum

      • SATA III: 6\,\text{Gb/s}\, (600\,\text{MB/s}) theoretical maximum (most common for modern HDDs and SATA SSDs)

      • Peripheral Component Interconnect Express (PCIe): A high-speed serial expansion bus. SSDs connected via PCIe offer significantly higher bandwidth than SATA.

      • Non-Volatile Memory Express (NVMe): A communication interface specification built on top of PCIe, designed specifically for SSDs to maximize parallel processing and reduce latency by communicating directly with the CPU.

    • Form-factors for SSDs:

      • M.2: A small form-factor connector for SSDs, Wi-Fi cards, etc. Available in various lengths (e.g., 22\,\text{mm}\, width \times 42\,\text{mm}\,/\text{60}\,\text{mm}\,/\text{80}\,\text{mm}\, lengths commonly M.2 2280).

      • mSATA: A smaller version of SATA, often found in older ultra-portable devices.

    • Drive configurations/RAID (Redundant Array of Independent Disks):

      • RAID 0 (Striping): Data is split into blocks and written across multiple disks. Offers improved performance (read/write) but no fault tolerance. If one disk fails, all data is lost. Requires a minimum of 2 disks.

      • RAID 1 (Mirroring): Data is duplicated (mirrored) on two or more disks. Provides excellent fault tolerance (tolerance for one disk failure) but halves usable capacity (e.g., two 1\ TB drives yield 1\ TB usable space). Requires a minimum of 2 disks.

      • RAID 5 (Striping + Parity): Data is striped across disks, and parity information is distributed among them. Offers good performance and fault tolerance (tolerance for one disk failure). Usable capacity is (N-1) \times \text{smallest disk size} (where N is the number of disks). Requires a minimum of 3 disks.

      • RAID 10 (1+0 - Nested Mirroring and Striping): Combines RAID 1 and RAID 0. Data is striped across mirrored sets. Provides high performance and excellent fault tolerance (survives multiple disk failures, as long as both drives in a mirrored pair don't fail). Requires a minimum of 4 disks.

    • Removable storage:

      • Flash drives (USB drives): Portable storage using flash memory, capacities ranging from 32\,\text{MB}\, to over 2\,\text{TB}. Hot-swappable with proper eject procedures.

      • Memory cards: SD, Mini-SD, Micro-SD (common for cameras, phones, drones); SDHC/XC (capacity classes: HC for High Capacity, XC for eXtended Capacity). Other legacy types like CompactFlash and xD.

      • Optical drives: CD-ROM, DVD-ROM, Blu-ray.

  • 3.4 Install & Configure Motherboards, CPUs, and Add-On Cards

    • Expansion cards: These cards extend the functionality of a computer by plugging into expansion slots on the motherboard.

      • Sound cards: Improve audio quality (higher fidelity DAC/ADC), offer surround sound, and digital outputs like S/PDIF for home theater systems beyond basic onboard audio.

      • Video/graphics cards (GPUs): Essential for displaying visuals. Can be onboard (integrated into CPU or motherboard, sharing system RAM) or add-in PCIe x16 cards (dedicated GPU with its own VRAM for superior performance).

      • Primary use-cases: Intensive gaming, professional imaging and CAD, high-resolution photo/video editing, and high-fidelity entertainment experiences.

      • Capture cards: Used for recording video from external sources (e.g., gaming consoles, camcorders, medical equipment) for DVR, live streaming, or surveillance systems.

      • Network Interface Cards (NICs): Enable network connectivity.

      • Wired: Ethernet standards like 10/100/1000\,\text{Mb/s}\, (Fast Ethernet/Gigabit Ethernet) are standard; higher-speed options include 2.5\,/5\,/10\,\text{Gb/s}\, Ethernet for faster local network transfers.

      • Wireless: Adhere to 802.11\,\text{a/b/g/n/ac/ax}\, Wi-Fi standards. Available as PCIe or mini-PCIe modules for laptops.

      • I/O (Input/Output) cards: Provide additional ports not available on the motherboard.

      • Additional USB 3.x\,/USB-C ports for more modern peripherals.

      • eSATA & Thunderbolt adapters for high-speed external storage and display connections.

Configuring Expansion Cards

  • Every adapter requires certain system resources like Interrupt Request (IRQ) lines, I/O port addresses, Direct Memory Access (DMA) channels, and memory addresses to function properly and avoid conflicts.

  • Plug and Play (PnP): A technology that allows the operating system (OS) to automatically detect and configure new hardware by negotiating resource assignments to prevent conflicts. Manual override via Unified Extensible Firmware Interface (UEFI/BIOS) settings is sometimes required for troubleshooting or specific configurations.

  • Manufacturer utilities: Software provided by the card manufacturer to allow firmware updates, advanced configuration (e.g., GPU overclocking), diagnostic tools, and specific controls like audio mixer settings for sound cards.

General Installation Workflow

  1. Preparation: Power off and unplug the system from the AC outlet. Take ESD (Electrostatic Discharge) precautions, such as using an anti-static wrist strap connected to a grounded surface (e.g., the metal chassis of the PC).

  2. Insertion: Carefully insert the expansion card into an open, matching expansion slot on the motherboard (e.g., PCIe x16 for graphics cards, PCIe x1 for smaller cards, legacy PCI, or M.2 for NVMe SSDs). Ensure it's fully seated.

  3. Securing & Power: Secure the card with its bracket to the case, often with a screw or clip. Connect auxiliary power cables (e.g., 6\,/8\,\text{-pin}\, PCIe power connectors) especially for high-draw GPUs, or internal USB cables for capture cards.

  4. Re-assembly & Boot: Carefully close the computer case. Reconnect power and peripheral cables. Boot the system.

  5. Driver Installation: Allow the OS to detect the new hardware. Install the latest signed drivers from the manufacturer's website; while PnP may auto-detect, specific drivers ensure full functionality and stability.

  6. Verification & Troubleshooting: Verify successful detection and functionality in Device Manager (Windows) or using lsusb/lspci commands (Linux). If malfunctions persist (e.g., no display, audio issues), check UEFI/BIOS settings, reinstall drivers, or consult the vendor utility.

  7. Documentation: Document any changes made to the system, including card model, slot used, and driver version, for future troubleshooting.

Hard-Disk Drive (HDD) Systems

  • Core Components

    • Controller electronics: Onboard circuitry that manages the drive's operations, including reading/writing data and communicating with the host system.

    • Hard disk assembly (HDA): The sealed unit containing the platters, read/write heads, and actuator arm, protected from contaminants.

    • Host Bus Adapter (HBA): The interface on the motherboard (or as an add-in card) that allows the CPU to communicate with the storage device (SATA/PATA).

  • Interface Types

    • Parallel ATA (PATA/IDE): An older, parallel interface using a 40\, or 80\,\text{-wire}\, ribbon cable. Limited by cable length and master/slave configuration.

    • Serial ATA (SATA): A newer, serial interface with thinner cables, higher speeds, and hot-plugging capabilities. (Speeds detailed under 3.3 Communication Interfaces).

Internal Anatomy (Conventional Drive)

  • Platters: Circular, rigid aluminum or glass discs coated with a magnetic material on which data is stored. Multiple platters are stacked on a spindle.

  • Read/Write heads: Tiny inductive/resistive devices located on the ends of actuator arms that float just microseconds above the platters to read or write magnetic data.

  • Actuator arm: A mechanical arm that moves the read/write heads across the platters.

  • Tracks: Concentric circles on the platter surface where data is stored. Each track is further subdivided.

  • Sectors: The smallest physical storage unit on a disk, traditionally 512\,\text{B}\, each. Modern drives use Advanced Format (AF) with 4096\,\text{B}\, sectors (also known as 4\, KB sectors).

  • Cylinder: A vertical collection of identical tracks across all platters at a given head position.

  • Cluster/Allocation Unit: The smallest block of disk space that the operating system can manage when storing files. It consists of one or more contiguous sectors.

Performance Metrics

  • Rotational speeds: Higher RPM (revolutions per minute) directly correlates to lower average latency (time to position the head over the desired sector) and faster data access. (Speeds noted under 3.3).

  • Average seek time: The average time taken for the read/write heads to move from one random track to another.

  • Cache size (buffer): A small amount of RAM on the drive that stores frequently accessed data or data waiting to be written, improving burst performance.

  • SATA revision: Defines the maximum theoretical throughput of the interface.

Solid-State Drives (SSD)

  • Advantages

    • Near-zero seek latency: Instantaneous data access due to no mechanical movement, leading to significantly faster boot times, application loading, and file transfers.

    • No moving parts: Makes them silent, highly resistant to physical shock, generates less heat, and consumes less power compared to HDDs.

    • High data density: More storage can be packed into smaller form factors.

  • Disadvantages

    • Higher \$/GB cost: Historically more expensive per gigabyte, though the gap is continuously shrinking.

    • Finite program/erase cycles: NAND flash cells can only be written to and erased a limited number of times before degrading. This is mitigated by:

      • Wear-levelling: A technique that evenly distributes write operations across all flash blocks to maximize drive longevity.

      • Over-provisioning: A portion of the SSD's total capacity is reserved and not accessible to the user, used by the SSD controller for wear-levelling, bad block management, and garbage collection, improving performance and endurance.

Communication Interfaces

  • SATA III (AHCI protocol): The Advanced Host Controller Interface is a standard for SATA devices. While widely compatible, it caps SSD sequential read/write speeds near 600\,\text{MB/s}\, due to the interface's bandwidth limitations.

  • PCIe lanes (x2, x4): SSDs connected via PCIe utilize multiple lanes (e.g., 2 or 4 PCIe lanes) directly connected to the CPU or chipset, enabling much higher bandwidth, often reaching multi-GB/s sequential reads and writes.

  • NVMe: The Non-Volatile Memory Express protocol is designed from the ground up to take full advantage of PCIe SSDs' parallelism and low latency, significantly outperforming AHCI for high-performance storage.

  • Legacy mSATA vs. modern M.2: While mSATA used the mini-PCIe physical connector, modern M.2 uses a dedicated slot and can support both SATA and NVMe protocols (distinguished by keying: B, M, or B+M keys).

Form Factors

  • 2.5-in SATA: The most common SSD form factor, designed to be a direct drop-in replacement for traditional 2.5\,\text{in}\, laptop HDDs.

  • mSATA: A small form-factor SSD (approximately the size of a business card) that plugs into a mini-PCIe slot, often found in older ultrabooks and embedded systems.

  • M.2 2280/2260/2242: A gumstick-shaped form factor. The numbers denote width (22\,\text{mm}) and length (80\,\text{mm}\,/\text{60}\,\text{mm}\,/\text{42}\,\text{mm}) respectively. Longer M.2 drives typically offer more NAND flash chips and higher capacity.

RAID Fundamentals

  • RAID 0 (Striping): Provides performance benefits by interleaving data segments across multiple physical drives. No data redundancy. Best for applications prioritizing speed where data loss is acceptable.

  • RAID 1 (Mirroring): Creates an exact duplicate of data on a second drive. Offers high data redundancy and read performance (can read from either drive) but sacrifices half of the total capacity. Ideal for critical systems that require high availability.

  • RAID 5 (Striping + Parity): Stripes data and distributes parity blocks across all drives. Allows for the loss of any single drive without data loss. Rebuilding a failed drive can be slow. Good balance of performance, capacity, and redundancy.

  • RAID 10 (1+0 - Nested Mirroring of Striped Sets): A combination of RAID 1 and RAID 0. Data is first striped across a set of drives (RAID 0), and then this striped set is mirrored (RAID 1). It offers the best performance and excellent fault tolerance (tolerance for multiple drive failures, provided they are not in the same mirrored pair). Requires a minimum of 4 disks, making it more expensive.

  • Striping (RAID 0, RAID 5, RAID 10 components) improves throughput by parallelizing I/O operations across multiple disks. Parity (RAID 5) and mirroring (RAID 1, RAID 10) supply fault tolerance and data protection.

Removable Storage & Media

  • Flash Memory

    • USB thumb drives (also called flash drives or jump drives): Highly portable solid-state storage devices with capacities ranging from as low as 32\,\text{MB}\, to 2\,\text{TB}\, and beyond. Connect via USB ports.

    • SD cards: Include standard SD, Mini-SD, and Micro-SD formats. Used in digital cameras, smartphones, drones, and other portable devices.

      • SDHC (Secure Digital High Capacity): Up to 32\,\text{GB}\,.

      • SDXC (Secure Digital eXtended Capacity): Up to 2\,\text{TB}\,.

    • CompactFlash (CF) and xD-Picture Card (xD): Older, mostly legacy memory card formats, though CF is still used in some professional cameras.

  • Hot-swappable: Most removable storage devices can be safely connected and disconnected while the computer is running, but the operating system's proper un-mount/eject procedure should always be followed to prevent data corruption or loss, especially from write-cache not being flushed.

Optical Drives

  • Compact Disc Read-Only Memory (CD-ROM): Stores approximately 700\,\text{MB}\, of data. Read-only.

  • Digital Versatile Disc Read-Only Memory (DVD-ROM): Stores approx. 4.7\,\text{GB}\, (single-layer) or 8.5\,\text{GB}\, (dual-layer). Read-only.

  • Blu-ray Disc Read-Only Memory (BD-ROM): Stores up to 25\,\text{GB}\, (single-layer), 50\,\text{GB}\, (dual-layer), or up to 100\,\text{GB}\, (BDXL) for archival and high-definition media. Read-only.

  • Mostly considered legacy storage technology for modern computing but still relevant for software distribution (e.g., OS installation media), archival storage, and diagnostics/bootable media.

Power Supplies (PSU)

  • Input

    • Voltage selection: PSUs typically accept either 115\,\text{V}\,\text{AC}\, (for North America/Japan) or 220\,\text{V}\,\text{AC}\, (for Europe/Asia and other regions) as input. Some PSUs have a manual switch, while others feature auto-switching.

    • Active PFC (Power Factor Correction): Modern PSUs often include active PFC, which automatically senses input voltage and improves power efficiency by reducing reactive power, leading to higher efficiency and less wasted energy.

  • DC Output Rails

    • Voltage rails: The PSU converts AC input into various DC voltages required by computer components.

      • +3.3\,\text{V}\,: Primarily used for RAM and some motherboard components.

      • +5\,\text{V}\,: Used by legacy components, USB devices, SSDs, and some logic circuits on the motherboard.

      • +12\,\text{V}\,: The major load for high-power components like the CPU (via EPS12V connector) and powerful graphics cards (via PCIe power connectors), and also powers motors in HDDs/fans.

    • Combined wattage rating: Indicates the total continuous power (in watts, e.g., 650\,\text{W}\,) the PSU can reliably supply to all components. Efficiency is rated by 80\,\text{PLUS}\, certification (e.g., Bronze, Gold, Platinum), indicating how efficiently AC power is converted to DC power (higher percentage is better).

  • Connectors

    • AT (legacy P8/P9): Older standard, separate P8\, and P9\, connectors for the motherboard. Largely obsolete.

    • ATX12V: The modern standard.

      • 20\, or 24\,\text{-pin}\, main power connector for the motherboard. The 24\,\text{-pin}\, connector is backward compatible with 20\,\text{-pin}\, boards.

      • 4\,\text{-pin}\, or 8\,\text{-pin}\, ATX12V/EPS12V connectors specifically for CPU power delivery.

    • PCIe 6\, or 8\,\text{-pin}\,: Dedicated power connectors for high-end graphics cards.

    • SATA power: 15\,\text{-pin}\, flat connector for SATA hard drives and SSDs.

    • Molex Peripheral (4\,\text{-pin}\,): Older connector for fans, optical drives, and some older peripherals.

Modular & Redundant PSUs

  • Modular PSUs: Allow you to detach unused cables, leading to better airflow within the computer case, improved cable management, and custom cable lengths. Available in fully modular (all cables detachable) or semi-modular (main power cable is fixed).

  • Redundant PSUs: Typically found in servers and mission-critical systems. They consist of multiple hot-swappable PSU modules that operate in parallel. If one unit fails, the others continue to supply power, preventing downtime. They often feature load-sharing to distribute the power load evenly.

Uninterruptible Power Supplies (UPS)

  • Function: Provides battery backup power in the event of a power outage and surge protection against voltage spikes.

  • Ratings: Rated in volt-ampere (VA) for apparent power and watt (W) for real power. When choosing a UPS, select one with a wattage rating at least \ge \frac{\text{total load (W)}}{0.8} to account for power factor (which is typically around 0.8\, for computer systems) and provide a buffer.

  • Features:

    • Automatic Voltage Regulation (AVR): Stabilizes fluctuating input voltages (sags or surges) without switching to battery power, prolonging battery life.

    • USB/serial monitoring: Allows the UPS to communicate with the computer, providing status updates, battery life, and power consumption data.

    • Graceful OS shutdown scripts: Enables the UPS to automatically initiate a safe shutdown of the operating system when power is lost and battery levels are low, preventing data corruption.

    • Phone/ethernet surge jacks: Provide surge protection for network and telephone lines passing through the UPS.

Practical & Ethical Considerations

  • Proper ESD handling (e.g., using anti-static wrist straps, mats, working on grounded surfaces) is crucial to prevent latent hardware defects caused by electrostatic discharge, which can lead to unpredictable component failures over time.

  • Data integrity: While RAID configurations offer redundancy, they are not a substitute for comprehensive backup strategies. Always maintain offline or cloud copies of critical data. RAID protects against disk failure, not against accidental deletion, malware, or catastrophic events.

  • Energy efficiency: PSUs with 80$$\,\text{PLUS}\, certification (e.g., Bronze, Gold, Platinum, Titanium) indicate higher efficiency in converting AC to DC power, which lowers operating costs, reduces heat output, and minimizes environmental footprint.

  • Secure disposal: Proper disposal of magnetic (HDDs) and solid-state media (SSDs, flash drives) is essential to protect Personally Identifiable Information (PII) and comply with data privacy regulations like GDPR and HIPAA. Methods include degaussing (for HDDs only), physical destruction (shredding/crushing), or cryptographic erase (for self-encrypting drives).