Approaches to slightly raise this limit assuming 32-bit arithmetics or 4096-byte sectors are not officially supported, as they fatally break compatibility with existing boot loaders and most MBR-compliant operating systems and system tools, and can cause serious data corruption when used outside of narrowly controlled system environments. The organization of the partition table in the MBR limits the maximum addressable storage space of a partitioned disk to 2 TiB (2 32 × 512 bytes). This MBR code is usually referred to as a boot loader. The MBR also contains executable code to function as a loader for the installed operating system-usually by passing control over to the loader's second stage, or in conjunction with each partition's volume boot record (VBR). The MBR holds the information on how the logical partitions, containing file systems, are organized on that medium.
The concept of MBRs was publicly introduced in 1983 with PC DOS 2.0.
For the first sector on non-partitioned media, see volume boot record.Ī master boot record ( MBR) is a special type of boot sector at the very beginning of partitioned computer mass storage devices like fixed disks or removable drives intended for use with IBM PC-compatible systems and beyond. This article is about a PC-specific type of boot sector on partitioned media.
