Fixed Block Architecture
Encyclopedia
Fixed Block Architecture (FBA) is a disk layout in which each addressable record (block
) on disk is of the same size. The term fell out of use, since nearly all modern disk drives use this principle, termed logical block addressing
and usually having a constant addressable block size of 512 bytes.
systems' disks, called DASD
, had traditionally been addressable in a form MBBCCHHR (extent-Bin-Cylinder-Head-Record, which was capable of storing records of varied size. Besides direct addressing, programmers were able to search by key, using the underlying count-key-data (CKD) structure.
Various IBM FBA devices featured block sizes of 512, 1024, 2048, and 4096.
(SATA) or Serial attached SCSI
(SAS) use logical block addressing
.
Block (data storage)
In computing , a block is a sequence of bytes or bits, having a nominal length . Data thus structured are said to be blocked. The process of putting data into blocks is called blocking. Blocking is used to facilitate the handling of the data-stream by the computer program receiving the data...
) on disk is of the same size. The term fell out of use, since nearly all modern disk drives use this principle, termed logical block addressing
Logical block addressing
Logical block addressing is a common scheme used for specifying the location of blocks of data stored on computer storage devices, generally secondary storage systems such as hard disks....
and usually having a constant addressable block size of 512 bytes.
Count Key Data
IBM mainframeIBM mainframe
IBM mainframes are large computer systems produced by IBM from 1952 to the present. During the 1960s and 1970s, the term mainframe computer was almost synonymous with IBM products due to their marketshare...
systems' disks, called DASD
Direct access storage device
In mainframe computers and some minicomputers, a direct access storage device, or DASD , is any secondary storage device which has relatively low access time relative to its capacity....
, had traditionally been addressable in a form MBBCCHHR (extent-Bin-Cylinder-Head-Record, which was capable of storing records of varied size. Besides direct addressing, programmers were able to search by key, using the underlying count-key-data (CKD) structure.
FBA
In IBM's implementation, a disk drive that stores data in blocks of fixed size. These blocks are addressed by block number relative to the beginning of the file.Various IBM FBA devices featured block sizes of 512, 1024, 2048, and 4096.
Hard Disk Drives
Modern HDD serial interfaces, i.e., Serial ATASerial ATA
Serial ATA is a computer bus interface for connecting host bus adapters to mass storage devices such as hard disk drives and optical drives...
(SATA) or Serial attached SCSI
Serial Attached SCSI
Serial Attached SCSI is a computer bus used to move data to and from computer storage devices such as hard drives and tape drives. SAS depends on a point-to-point serial protocol that replaces the parallel SCSI bus technology that first appeared in the mid 1980s in data centers and workstations,...
(SAS) use logical block addressing
Logical block addressing
Logical block addressing is a common scheme used for specifying the location of blocks of data stored on computer storage devices, generally secondary storage systems such as hard disks....
.