For the uninitiated, understanding SSD specifications can be a maze of jargon and numbers. This article will demystify these terms and specifications, helping you make an informed decision when purchasing an SSD.
The Form Factor: Size Matters
When selecting an SSD, the first thing to consider is the form factor. Essentially, an SSD’s form factor refers to its physical dimensions and layout. It’s crucial to match the SSD’s form factor with the space available in your system to ensure compatibility.
2.5-inch SSDs
The 2.5-inch SSD form factor is the most prevalent, often found in both desktops and laptops. This form factor is identical to that of standard laptop HDDs, making 2.5-inch SSDs an easy drop-in replacement in many systems.
3.5-inch SSDs
Though less common, 3.5-inch SSDs also exist, primarily designed for enterprise-grade usage. They offer a larger physical size, often translating to increased storage capacity.
M.2 SSDs
The M.2 form factor, previously known as Next Generation Form Factor (NGFF), is significantly more compact than traditional 2.5-inch drives. The size of an M.2 SSD is roughly that of a stick of chewing gum, making it a perfect fit for laptops and small-form-factor desktops. M.2 SSDs are categorized by a number designation, such as 2230, with the first two digits representing the width, and the last two the length (in millimeters).
Making the Connection: Connector Types
After the form factor, the type of physical connector used by the SSD is another vital specification to look at. Different motherboards will feature different types of slots, so it’s crucial to verify which connectors your system supports.
SATA
The Serial Advanced Technology Attachment (SATA) connector is a standard feature on modern motherboards. Both 2.5-inch and 3.5-inch SSDs commonly use SATA connectors.
M.2
In addition to being a form factor, M.2 is also a type of physical connector for SSDs. Some motherboards come with built-in M.2 slots, allowing M.2 SSDs to be directly inserted without needing any cables. Note that M.2 SSDs can utilize either SATA or PCIe interfaces.
Interface Intricacies
An SSD’s interface is responsible for the communication between the drive and the computer. It plays a significant role in the efficiency of data transfer.
- SATA: SATA interfaces are an improvement over their predecessors due to their serial connection, which doesn’t require synchronization of data. However, SATA SSDs have a maximum transfer speed of around 500 Mbps, limiting their performance compared to newer interfaces.
- PCIe: Peripheral Component Interconnect Express (PCIe) is a notable upgrade over SATA. Unlike SATA, designed specifically for storage, PCIe connects directly to the CPU, offering much higher transfer speeds of up to 1GB/s.
Communication Protocols: Speaking the Same Language
The communication protocol used by an SSD interface is essentially the “language” it uses to communicate with the CPU.
- AHCI: Advanced Host Controller Interface (AHCI) is an older, slower protocol used with SATA drives. It’s gradually being phased out in favor of NVMe.
- NVMe: Non-Volatile Memory Express (NVMe) is a protocol designed specifically for SSDs. It operates on top of the PCIe bus interface and allows for significantly higher queue commands, reducing CPU overhead, and improving performance.
In Summary;
| Drive Name | 2.5" SATA | 3.5" SATA | M.2 SATA | M.2 NVMe |
|---|---|---|---|---|
| Form Factor | 2.5 | 3.5 | M.2 | M.2 |
| Connector | SATA | SATA | M.2 | M.2 |
| Interface | SATA | SATA | SATA | PCIe |
| Protocol | AHCI | AHCI | AHCI | NVMe |
Memory Components: The Building Blocks
Modern SSDs use NAND (Not AND) flash memory to store data even when the power is off. Currently, SSDs on the market utilize Single-Level Cell (SLC), Multi-Level Cell (MLC), Triple-Level Cell (TLC), and Quad-Level Cell (QLC) NAND flash memory.
SLC/MLC/TLC/QLC NAND
The naming of these technologies refers to the number of bits stored in each cell. SLC is the fastest and most durable but also the most expensive, storing one bit per cell. MLC stores two bits per cell, while TLC stores three, and QLC stores four, being the slowest, least durable, but also the most cost-effective.
3D NAND
3D NAND is not a different type of NAND but a production process that stacks memory cells vertically across multiple layers. This increases storage density per bit, improving performance and durability while reducing power consumption.
In conclusion, understanding SSD specifications can seem daunting. However, by breaking it down into key areas – form factor, connector type, interface, communication protocol, and memory components, you can make sense of the jargon and select the right SSD for your needs.
SSD Endurance
SSD endurance is usually specified in the form of a number followed by TBW, which stands for terabytes written. Read more about how to interpret these numbers in our article on SSD endurance.
See also