What Is MBR or What Is Master Boot Record

MBR, Master Boot Record, is a boot sector at the very beginning of computers' hard drives. The concept of MBRs was publicly introduced in 1983 with DOS 2.0.

MBR records the information of all partitions. And the information includes file systems, partition size and organization, etc. In addition, it also contains execute code, or it is used to connect each partition's volume boot record (VBR). This MBR code is often referred to as the boot loader for installed operating systems.

The maximum addressable storage space of MBR partition table is 2TB (2^32×512 bytes). Therefore, the MBR-based partitioning scheme is gradually being replaced by the GUID Partition Table (GPT) scheme.

MBR cannot exist on non-partitioned media like floppies.

When you get a new hard drive, you need to initialize it to MBR disk or GPT disk. Here, if you want to initialize it to MBR disk, you can use MiniTool Partition Wizard and its "Initialize to MBR Disk" function to do this job.

The Analysis of Partition

In general, there are two kinds of definition for MBR. Broadly speaking, MBR contains the entire sector (bootstrap, partition table and separation identifier). While in a narrow sense, it only refers to bootstrap.

MBR consists of three parts, including main boot loader, hard disk partition table (DPT) and effective signature (55AA). And the partition table subdivides a storage medium using unites of cylinders, heads and sectors.

MBR (Master Boot Record)

Note: MBR does not belong to any operating system. Therefore, the disk command cannot read it. However, users can modify or rewrite it via commands. For example, in the minix 3, users can use the “installboot-m/dev/c/us/r/mdec/masterboot' command to write the master-boot program into MBR.

The Component of MBR

A master boot record consists of 4 parts including master boot program, error message data area, disk partition table, and end signature. The master boot program is responsible for loading and running the system. The partition table describes the partitions of a storage device.

Virtual MBR

Virtual MBR refers to extended boot record (EBR), whose record entries are identical to MBR's.

Rebuild MBR

In some case, mistaken operation or computer virus invasion may damage MBR. As a result, when launching computer, users just see a black screen or see some nonsense letters. Aiming at this situation, they can turn to some solutions, like:
DOS commands: fdisk /mbr
Third party software: MiniTool Partition Wizard