Enterprise 2.5″ SAS and 3.5″ SAS hard drives are available from OEMs such as HP, Dell and Lenovo in or out of caddy depending on your requirements. Small Form Factor (SFF) SAS disk drives are generally preferred for high performance storage servers as the drive is shorter than it’s 3.5″ brother, the platter area is smaller meaning it can perform up to 50% better than a large form factor SAS drive, even at the same RPM whether it be 10K or 15K.