A 3.5 solid-state drive (SSD) is a data storage device that is designed to use the 3.5-inch hard disk drive (HDD) form factor. A 3.5-inch SSD fits into the same drive bay as an identically sized HDD in a portable computer (PC), enterprise server, or storage system.
HDDs and SSDs are available in a variety of form factors, including 3.5-inch, which is also known as large form factor (LFF), and 2.5-inch, which is also known as small form factor (SFF). The 3.5-inch and 2.5-inch measurements represent the approximate diameter of the HDD platter within the drive enclosure.
Industry standards dictate options for the width, depth and height of a 3.5-inch SSD and for the host interface connector. A 3.5-inch SDD is typically four inches (101 millimeters) in width, 5.75 inches (146 millimeters) in depth and one to 1.63 inches (25 millimeters to 41 millimeters) in height. The 3.5-inch SSD typically uses the serial-attached SCSI (SAS) or serial ATA (SATA) interface to transfer data to and from the host computing system.