Side-by-Side Comparison
SSD
M.2 vs. U.2
Comparing 2 standards across 9 specifications. 9 key differences identified.
Comparing:
M.2
U.2
M.2 is the dominant SSD form factor today, sized by a code like 2280 (22mm wide, 80mm long). B-key supports SATA or PCIe x2; M-key supports full PCIe x4 NVMe speed; B+M-key dual-notch modules are actually capped at PCIe x2, not the full x4 the two notches might suggest.
U.2 uses the SFF-8639 connector to bring PCIe x4 NVMe speeds to a 2.5-inch, hot-swappable drive body -- the enterprise and datacenter counterpart to consumer M.2, trading M.2's compact size for better cooling, higher power delivery, and the ability to swap drives without powering down.
Specification Comparison Table
9 Parameters| Parameter / Spec | ||
|---|---|---|
|
Common Sizes
|
2230, 2242, 2260, 2280, 22110 | — |
|
B-Key
|
SATA or PCIe x2 | — |
|
M-Key
|
SATA or full PCIe x4 (NVMe) | — |
|
B+M-Key (dual notch)
|
SATA or PCIe x2 only -- not x4 | — |
|
Introduced
|
November 2013 (as "NGFF") | — |
|
Connector
|
— | SFF-8639 |
|
Max PCIe Lanes
|
— | x4 (same NVMe electrical spec as M.2 M-key) |
|
Power Rails
|
— | 3.3V, 5V, 12V (vs. M.2's 3.3V only) |
|
Hot-Swap
|
— | Yes |