Blocks

In computing, block size indicates a nominal size, usually expressed in bytes or bits, of a mass of data. Data thus controlled is said to be blocked. The process of putting data into blocks is called blocking. Blocking is used to assist the handling of the data-stream by the computer program receiving the data. Blocked data is generally read a block at a time. Blocking is almost universally employed when storing data to 9-track magnetic tape, to turning media such as floppy disks, hard disks, and optical discs, and to NAND flash memory.

Block storage is normally abstract by a file system or database management system for use by applications and end users. Database management systems(DBMS) often use their own Block I/O for superior performance and recoverability as compare to layering the DBMS on top of a file system.