Fixed-block architecture (
FBA) is an IBM term for the
hard disk drive (HDD) layout in which each addressable
block (more commonly, sector) on the disk has the same size, utilizing the well-established
three-number block addressing scheme. FBA as a term was created and used by
IBM for its HDDs beginning in 1979 to distinguish such drives as IBM transitioned away from their variable record size format used on
IBM's mainframe hard disk drives beginning in 1964 with its
System/360; later, FBA evolved into the
logical block addressing (LBA), which is a linear block addressing scheme for the fixed length blocks.