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.
