By PURPLELEC | 18 January 2025 | 0 Comments
Detailed Explanation of SSD Form Factor and Interface
I. SSD Form Factor
SSD (Solid State Drive) is mainly divided into two types: internal and external. Among them, internal SSD has three main specifications: 2.5-inch, M.2 and mSATA.
1. 2.5-inch SSD
For more than two decades, the 2.5-inch SSD size has been the standard.
Originally designed to replace HDDs (hard disk drives) of the same size to simplify the transition and reduce the need to replace the connecting interface cables.
2. M.2 SSD
M.2 is the smallest size of SSD, about the size of a piece of chewing gum.
Typically supports the highest read and write speeds due to its interface design.
The M.2 slot on the motherboard can be connected to the PCIe or SATA interface, but PCIe NVMe SSDs are the most popular due to their speed advantages.
3. mSATA SSD
The size of an SSD with an mSATA form factor is one-eighth of a 2.5-inch hard drive.
Designed to plug into the mSATA slot on the system motherboard, it is often used in ultra-thin and mini devices, or as a secondary hard drive for desktop computers.
4. External SSD
Compatible with a variety of devices via USB cable.
Portable SSD internal technology is similar to internal hard drives, but has a durable shell and USB cable interface.
"External" and "portable" are often used interchangeably when describing storage drives that are not installed inside the system, but not all external SSDs are designed for portability.
II. SSD interface
The speed of an SSD depends not only on the form factor, but also on its interface, that is, how it connects to the system.
1. Serial ATA (SATA)
The most common SSD interface, usually used for 2.5-inch SSDs.
Uses the Advanced Host Controller Interface (AHCI) command protocol designed for mechanical HDDs.
Hot-swap capabilities and the ability for users to quickly replace drives are its important features.
The latest generation offers transfer rates of up to 6GB/s.
2. PCI Express® (PCIe)
A newer high-speed serial bus interface with a smaller physical footprint.
Uses multiple channels to connect storage devices, exchanging data faster than SATA connections.
Used with M.2 SSDs.
3. NVMe
Non-volatile memory standard (NVM Express), a communication protocol specifically designed to work with flash memory using the PCIe bus.
Uses the parallel nature of SSDs, combined with the increased read and write speeds of the PCIe bus and NAND technology, to create faster non-volatile storage.
Combined with the PCIe connection in the SSD, it can achieve read and write speeds 4 times faster than SATA SSDs using the SCSI protocol.
4. USB
Almost every computer is equipped with a USB connection, making it an ideal interface for portable storage drives.
Data transfer speeds are affected by the USB version and the cable transfer rate.
5. Thunderbolt
An interface connection designed between Intel® and Apple® for connecting peripherals to a computer.
The latest generation, Thunderbolt 3, shares the same reversible port as USB-C and is backward compatible.
III. SSD Generation and Acceleration
SSDs are also improving from generation to generation, and now you can choose third-generation, fourth-generation, or Gen5 SSDs.
SSDs are backward compatible, but you won't be able to reach top speeds when running a new generation of SSDs on an older computer.
Gen3 SSDs have a top speed of about 3,500MB/s, and Gen4 SSDs are 2 times faster at about 7,000MB/s.
Other factors such as storage, firmware, TRIM, and drive health can also affect the speed of an SSD.
It is recommended to keep 10-15% of free space to balance performance and storage.
Keeping the firmware updated helps the SSD run at peak performance.
Conclusion
The speed of an SSD depends on a variety of factors, including the system, the generation of the SSD, the form factor, and the interface.
External SSDs cannot reach their maximum speeds using older connections such as USB-A.
Drive speed is directly affected by the interface, and SSD speeds vary greatly between different interfaces and specifications.
To get the best of both worlds, upgrade your PC with a fast internal SSD and pair it with a fast portable SSD for fast transfers and data backups.
Portable SSD: High-speed, portable and durable data storage solution
How to use an external SSD as a boot drive
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