SSD form factors

While HDDs are commonly 2.5 or 3.5 inches wide, and most SATA-based SSDs are 2.5 inches wide and 7mm thick, NVMe drives take on a number of new form factors that allow them to fit in a variety of devices.

•    M.2 - The reduction in physical drive size seen in the M.2 form factor guarantees the future ubiquity of these storage devices. 22 refers to the width and 30/42/80/110 refer to the length in millimetres. Currently, M.2 2280 supports SATA, it is also the most common NVMe SSD form factor for NVMe. As technology improves and shrinks, this may change.
•    U.2 - These are more costly storage devices with higher performance and endurance typically found in data center/enterprise storage environments.
•    Add-in PCIe cards - These high-performing NVMe SSDs found their way into systems that hadn’t yet adopted sockets to accommodate the M.2 form factor.

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