What is Master Boot Record or MBR? – POFTUT

What is Master Boot Record or MBR?

Master Boot Record is the start of an partition schema in disk file systems. In daily usage we use single physical disk by splitting it multiple partitions for different use cases. Operating systems needs some structure in order to use disk drives without problem. Partition schema provides some structure where operating systems obeys this structure.

Master Boot Record

MBR is first introduced in 1983 with the IBM PC DOS . At these days PC’s getting popular and need some standard for compability. DOS was the operating system of the first PC’s which is developed by Microsoft. MBR is designed to be used with all DOS installed and other operating systems.

First Sector

MBR is called the first sector of the disk. When a computer starts the BIOS will try to read this first sector and try to load related Operating system like Windows and Linux according to the information stored in this sector. MBR generally provide a link to the boot loader where more features can be presented to the operating system.

Windows Boot Loader

As Microsoft operating systems named Windows are very popular the most used boot loader for MBR is Windows Boot Loader.


Grub is popular boot loader generally provided by different Linux distributions. MBR can link to the Grub boot loader in order to load operating system. Grub can also load Windows operating systems easily.

MBR 2 TB Disk Limitation

In the old times disk drives do not have big sizes like 2 or 3 TB. 200MB was enough to use Windows 98 SE. In these days we generally use 1 TB and bigger disks. MBR is designed for 30 years ago so the disk size is the biggest problem for MBR. MBR can not address disks bigger than 2TB.

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Multiple Partitions Limitation

MBR disks may have multiple partitions but have some restrictions. MBR uses primary and logicial partitions. A disk may have up to 4 primary partitions. A primary partition holds logical partitions to create more partitions. A primary partition may have up 4 logical partitions.


In order to eliminate MBR 30 year old limitations GTP schema is developed. GTP disk schema can be used with all modern operating systems like Windows, Linux, MacOS etc. GTP eliminates partitions count and 2 TB disk size limitations. GPT also provide more features like CRC error check, error recovery etc.

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