Glossary U.2 By Chris Mellor - May 7, 2022 Twitter WhatsApp Linkedin ReddIt Email U.2 – a 2.5-inch standard storage drive bay in a rack enclosure and using an SFF-8639 connector with the PCIe, SATA and SAS protocols. It does not provide interchangeable SAS/SATA/NVMe support in the same slot.