What is a Solid State Drive (SSD)?
A solid state drive (SSD) is a storage device that saves your files, photos, and applications using memory chips instead of physical moving parts like an HDD. These chips are known as flash memory, and they can store data by harnessing electrical charges — even when powered off.
Unlike traditional hard drives with spinning parts, SSDs are — as their name implies — made of solid components. Without needing to wait for disks to start spinning or read/write heads to swing into place, solid state drives offer dramatically faster speeds, more durability, and better energy efficiency.
Flash memory and solid state technology have transformed computing, from loading games faster to muscling through heavy data center workloads like training foundational AI models.
Here’s what you need to know about using SSDs, as well as how they work and what they do best.
SSDs: What are They Used For?
Today, SSDs can be found backing up photos at home, powering content creators in the field, driving productivity at the office, and supporting the most advanced data centers in the world.
Their versatility and performance make them ideal for some of the most popular things we all do with our devices — for fun, for work, and everything in between.
Gamers
- Dramatically reduced loading times in games
- Smoother streaming of open-world environments
- Faster installation and game updates
- Easier game saves and reloading
Students
- Quick access to readings, projects, and more
- Responsiveness for big presentations
- Reliable storage for assignments and projects
- Improved battery life for laptop users
Content creators
- Near-instant access to emails and documents
- Faster processing of large spreadsheets
- Quick switching between multiple applications
- Reliable storage for critical business data
Business users
- Near-instant access to emails and documents
- Faster processing of large spreadsheets
- Quick switching between multiple applications
- Reliable storage for critical business data
Data centers
- High input/output operations per second (IOPS)
- Lower power consumption and cooling needs
- Improved reliability with no moving parts
- Powerful performance under heavy workloads
AI & LLM training
- Rapid access to training datasets
- Fast transfer of model weights and parameters
- Quick iteration during model development
- Efficient handling of temporary cache files
How Do SSDs Work?
Understanding how SSDs work requires looking at both their physical structure and the processes that manage your data. Let's break this down into layers, starting with the fundamental components and building up to what you experience as a user.
Physical Components of an SSD
| Component | Role | Analogy |
|---|---|---|
| NAND flash memory cells | Store data | Like billions of tiny switches that can hold electrical charges |
| Controller chip | Manages operations | The "brain" that coordinates all activities |
| Cache memory | Temporary storage | A quick-access workspace for the controller |
| Power circuits | Power distribution | The power grid of the drive |
| PCB (Circuit Board) | Connects components | The city streets connecting everything together |
SSD Memory Types
Several types of NAND flash memory exist, each with different characteristics:
- Single-Level Cell (SLC): Stores one bit per cell, offering the highest performance and durability but at a higher cost.
- Multi-Level Cell (MLC): Stores two bits per cell, providing a balance of performance and value.
- Triple-Level Cell (TLC): Stores three bits per cell, offering higher capacity at lower costs.
- Quad-Level Cell (QLC): Stores four bits per cell, maximizing storage density while sacrificing some performance.
How SSDs Write Data
When you save a file to your SSD, here's what happens step by step:
Initial request
- Your operating system sends a write command to the SSD controller.
- The controller acknowledges the request and prepares for the operation.
Data preparation
- The controller breaks your file into smaller chunks.
- It identifies available flash memory cells to store the data.
- The controller generates error correction codes to ensure data integrity.
Writing to flash cells
- The controller applies specific voltages to targeted memory cells.
- Electrons are trapped in the cells, changing their electrical state.
- This change in state represents your data in binary form.
Verification
- The controller reads back the written data.
- It compares this with the original data to ensure accuracy.
- Any discrepancies are corrected immediately.
How SSDs Read Data
When you open a file, the process works like this:
Search phase
- The controller consults its mapping table to locate your data.
- It identifies which flash memory cells contain the relevant information.
Data retrieval
- The controller reads the electrical states of the target cells.
- It converts these states back into binary data.
- Error correction codes verify data integrity.
Data assembly
- The controller reconstructs the complete file from multiple cells.
- It buffers this data in high-speed cache memory.
- The assembled data is sent to your computer's memory.
How SSDs Work for Users
All this technology and process management translates into real benefits:
| User action | What's happening inside | What you experience |
|---|---|---|
| Turning on your computer | Controller activates all systems and begins responding to requests | Near-instant access to your files |
| Opening a large file | Parallel reading from multiplre flash cells simultaneously | Files open significantly faster than average HDDs |
| Saving new work | Controller efficiently distributes data across available cells | Quick save times and reliable storage |
| Moving files | Data is read and written in parallel across many cells | Fast transfer speed |
SSDs: Pros and Cons
Understanding the key features of SSDs helps explain why they've become such a transformative storage technology. Let's examine their main advantages and limitations to help you make informed decisions about storage solutions.
Pros of SSDs
SSDs offer several significant benefits that make them attractive for many computing applications:
SSDs: Speed and performance
- Boot times faster than average HDDs
- Near-instant data retrieval with no moving parts
- Read speeds of several thousand MB/s
- Applications launch super fast
- Smoother multitasking under heavy loads
SSDs: Energy efficiency
- Less power consumption than HDDs
- No energy wasted on spinning platters
- Reduced cooling requirements
- Longer battery life in laptops
- Lower TCO in data centers
SSDs: Durability
- No mechanical parts to break or wear out
- Highly resistant to drops and physical shock
- Better performance in high-vibration environments
- More consistent performance over time
- Less susceptible to temperature fluctuations
SSDs: Silent operation
- Zero noise during operations
- Ideal for quiet environments
- Perfect for recording studios
- Great for home theater PCs
- Minimal vibration during use
Cons of SSDs
While SSDs offer many benefits, they also have some limitations to consider:
SSDs: Cost per TB
- Higher cost per gigabyte than HDDs
- Premium pricing for larger capacities
- More expensive enterprise solutions
- Higher initial investment required
- May need to balance capacity vs. budget
SSDs: Write endurance
- Limited number of write cycles per cell
- TLC/QLC drives have shorter lifespans
- Heavy workloads can impact longevity
- Wear-leveling needed to extend life
What are the Different Types of SSDs?
SSDs come in various forms and interfaces, each designed for specific use cases and performance requirements:
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SATA SSDs
Older but still reliable flash storage, SATA SSDs use the same interface as traditional hard drives. These offer good performance for everyday computing needs, though their speeds are limited by the SATA interface.
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NVMe™ SSDs
NVMe drives connect work directly with the PCIe bus, offering significantly higher speeds than SATA SSDs. They're ideal for high-performance computing, gaming, and professional applications where speed is crucial.
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USB SSDs
SSDs that use the latest USB protocols deliver rapid speeds while offering helpful compatibility across many USB devices. These SSDs excel at tasks like 4K video editing and gaming, though they require compatible ports to achieve their full potential.
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Thunderbolt SSDs
SSDs with Thunderbolt compatibility give users top-tier performance in external and portable form factors, offering consistently high bandwidth. They're ideal for creative professionals, though they require Thunderbolt ports to hit their top speeds.
SSD Form Factors
The physical design of SSDs has evolved to meet various computing needs:
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M.2 SSDs
Available in various lengths — like 2230 and 2280 — these compact drives mount directly to motherboards, saving space and power.
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Add-in SSD cards
These SSDs plug directly into PCIe slots, like graphics cards. They often offer high performance but require a dedicated, full-size PCIe slot.
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2.5-inch SSDs
A legacy form factor that mirrors the size of laptop hard drives. These are commonly used for upgrading existing systems while offering broad compatibility.
How Do SSDs Compare to HDDs?
When comparing SSDs to traditional HDDs several key differences emerge:
SSD vs. HDD: Performance
- SSDs usually have faster random access times
- SSDs usually have faser sequential read/write speeds
- SSDs typically handle multiple simultaneous requests better
- HDDs have slower boot and load times
SSD vs. HDD: Durability
- SSDs generally offer better physical durability but have write cycle limitations
- HDDs can write data indefinitely
- HDDs are more susceptible to physical damage
SSD vs. HDD: Cost per TB
- HDDs maintain an advantage in cost per gigabyte
- HDDs are preferred for bulk storage
- SSDs are often chosen for operating systems and frequently accessed data
SSD vs. HDD: Energy use
- SSDs consume less power than HDDs
- SSDs generate less heat than HDDs
SSDs and SanDisk
Solid state drives represent a significant advancement in storage technology, offering substantial performance improvements over traditional hard drives. While they may cost more per gigabyte, their benefits in speed, reliability, and energy efficiency make them increasingly popular.
SSDs are becoming the standard for primary storage in modern computing devices. Thanks to its innovations in NAND flash technology, SanDisk is pushing SSDs — from gaming consoles and home computers to creative work stations and data centers — towards higher performance, lower costs, and greater durability.
SSD for Gaming
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SSD for Creators
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SSD for NAS
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