SAS drive
Serial Attached SCSI — an enterprise interface for drives in servers and storage systems. Faster and more robust than SATA, with features like dual ports (redundancy), deeper queue handling, and support for many drives via expanders.
Difference from SATA: SAS controllers can run SATA drives, but not the other way around. SAS gives 12 Gbps (vs SATA 6), full-duplex, a dual port for failover paths, better error reporting (SCSI commands), and addresses thousands of devices via expanders. Use case: RAID arrays, SAN/DAS, critical server drives. An HBA (Host Bus Adapter) + backplane connects many drives. Tri-mode controllers handle SAS + SATA + NVMe in the same connector (U.2/U.3). In the HDD world SAS lives on for nearline storage; for flash, NVMe is gradually taking over the server role. On desktop nearly nonexistent — pure enterprise tech.