Master Boot RecordMaster Boot Record (MBR), or partition sector, is the 512-byte boot sector that is the first sector ("Sector 0") of a partitioned data storage device such as a hard disk. (The boot sector of a non-partitioned device is a Volume Boot Record.) It is sometimes used for bootstrapping operating systems, containing a machine code program; sometimes used for holding part of a disk's partition table[1]; and sometimes used for uniquely identifying individual disk media, with a 32-bit data signature; although on some machines it is entirely unused. |