SAS Stands for Serial Attached SCSI and is a Technology for Transferring Data from and to Hard Drives. SAS Whilst Refers to the Interface it’s Typically Used to Describe a Type of HDD, Usually 10K or 15K SAS. Hard Drives 2.5″ SFF & 3.5″ LFF are Almost Exclusively for Usage in Servers. that Use Hot Swappable (Hot-Swap) Drives with a SAS Hot Pluggable Backplane. You Use a Hard Drive Tray or Caddy or Sled. A Hard Disk Drive is a Non-Volatile Data Storage Device. HDD Usually Installed Internally in a Computer, Attached Directly to the Disk Controller of the Computer Motherboard. Hard Disk Contains One or More Platters, Housed Inside of an Air-Sealed Casing. Data is Written to the Platters Using a Magnetic Head, Which Moves Rapidly Over them as they Spin.