Internal and External Types of Secondary Memory Storage
Secondary Storage
Secondary storage is non-volatile memory used to store data permanently, even when the computer is turned off.
It holds files, applications, and the operating system for long-term use.
Internal Hard Drives
Solid State Drives (SSDs)
Solid State Drives (SSDs)
Solid State Drives (SSDs) are a type of non-volatile storage that use flash memory to store data. Unlike HDDs, SSDs have no moving parts, which makes them faster, more durable, and more energy-efficient.
- Speed: SSDs offer rapid data access and transfer speeds, often exceeding 500 MB/s for SATA SSDs and up to 7,000 MB/s for NVMe SSDs.
- Durability: The absence of moving parts makes SSDs more resistant to physical shock and wear.
- Power Efficiency: SSDs consume less power, making them ideal for laptops and mobile devices.
- SSDs use NAND flash memory, which stores data in floating-gate transistors.
- This technology allows data to be retained even when the power is off.
Solid State allows direct access to data. Like grabbing a book instantly off a shelf, no rummaging needed.
Hard Disk Drives (HDDs)
Hard Disk Drives (HDDs)
Hard Disk Drives (HDDs) are traditional storage devices that use magnetic platters and a read/write head to store and retrieve data.
- Capacity: HDDs offer large storage capacities at a lower cost per gigabyte compared to SSDs.
- Reliability: They are reliable for long-term storage but are slower due to mechanical parts.
- Use Cases: HDDs are commonly used in desktops, servers, and for bulk storage where speed is less critical.
- Magnetic Storage can only be accessed sequentially, so is slower in locating files.
- Like searching a filing cabinet with drawers and labeled folders, reliable but slower.
The average sustained data transfer rate for an HDD ranges from 100 MB/s to 200 MB/s, significantly slower than SSDs.
Embedded Multimedia Cards (eMMCs)
Embedded Multimedia Cards (eMMCs)
Embedded Multimedia Cards (eMMCs) are a type of flash storage integrated directly onto a device's motherboard.
- Performance: eMMCs are slower than SSDs but faster than HDDs, making them suitable for budget devices.
- Capacity: They typically offer lower storage capacities, ranging from 16 GB to 256 GB.
- Use Cases: eMMCs are commonly found in smartphones, tablets, and low-cost laptops.
eMMCs combine NAND flash memory with a controller in a single package, simplifying integration into devices.
External Storage Devices
External Hard Drives (SSD, HDD)
- External SSDs: Offer the same speed and durability benefits as internal SSDs, making them ideal for fast data transfer and backup.
- External HDDs: Provide large storage capacities at a lower cost, suitable for archiving and bulk storage.
External drives connect via interfaces like USB or Thunderbolt, allowing for easy portability and use across multiple devices.
Optical Drives
Optical drives
Optical drives read and write data to optical discs such as CDs, DVDs, and Blu-ray discs.
- Use Cases: Ideal for archiving data, distributing software, and media playback.
- Limitations: Slower data access speeds and limited storage capacity compared to modern alternatives.
Optical discs store data as pits and lands on a reflective surface, read by a laser in the drive.
Flash Drives
Flash drives
Flash drives, also known as USB drives, are portable storage devices that use NAND flash memory.
- Portability: Small and easy to carry, making them ideal for transferring files between devices.
- Capacity: Typically range from 8 GB to 1 TB.
- Limitations: Lower storage capacities and can be easily lost or damaged.
- Losing a flash drive with sensitive data can pose a significant security risk.
- Always encrypt important files.
Memory Cards
Memory cards
Memory cards are small, removable storage devices used in cameras, smartphones, and tablets.
- Types: Include SD cards, microSD cards, and CompactFlash cards.
- Use Cases: Ideal for expanding storage in portable devices and for easy file transfer.
Memory cards also use NAND flash memory and are available in various capacities and speed classes.
Network Attached Storage (NAS)
Network Attached Storage (NAS)
Network Attached Storage (NAS) devices provide centralized storage accessible over a network.
- Features: Often include RAID configurations for data redundancy and can be accessed by multiple devices simultaneously.
- Use Cases: Ideal for home networks, small businesses, and media streaming.
NAS devices can be expanded by adding additional drives, making them a scalable storage solution.
Scenarios for Different Types of Storage
- Internal SSDs: Used in laptops and high-performance desktops for fast boot times and application loading.
- Internal HDDs: Common in servers and desktops for bulk storage of large files.
- eMMCs: Found in budget devices where cost and space are constraints.
- External SSDs: Ideal for photographers and videographers who need fast, portable storage.
- External HDDs: Used for backups and archiving large data sets.
- Optical Drives: Employed for media playback and archival storage.
- Flash Drives: Convenient for transferring files between computers.
- Memory Cards: Used in cameras and smartphones for expandable storage.
- NAS: Provides centralized storage for homes and businesses, enabling file sharing and data backup across multiple devices.
When choosing a storage solution, consider factors such as speed, capacity, durability, and cost to match the specific needs of your application.
Most desktop computers will have mixed storage types for different scenarios.
For example a person might be an amateur photographer that enjoys playing video games and professionally works as a software developer.
Their desktop could be configured to have the following:
- Main SSD: Connected through M.2 (internal) to the mother board
- This would be used for the OS and the main System Files
- Secondary SSD: Connected through a Sata cable (internal) to the motherboard
- This could be a lower spec SSD but with more capacity to store and run computer games (large and require high speed access)
- HDD: Connected to the motherboard through a Sata cable (internal)
- This would be a large drive available to store the RAW image files and edited photos (large files but do not require high speed access)
- Memory Card: External memory card reader for the SD Card from the camera
- For transferring photos taken on the camera to the computer so that they can be edited and saved
- External HDD: Connected through USB 3
- For backing up the photos and keeping them in a secondary location
- External Memory Stick: Connected through USB 3
- For transferring select photos from a trip to view on another device e.g. on a TV with their family.
