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Saturday, 20 December 2014

MBR (Master Boot Loader)

MBR is the Master Boot Loader which is located at first sector of the hard disk used to find the operating system and load it into the memory.

The MBR can be created automatically when you create the partitions.

The size of MBR is 512 bytes which contains:

(i)                 Primary Boot Loader (446 Bytes)
(ii)               Partition table (64 Bytes)
(iii)             MBR Validation Check/Magic Number (2 Bytes)

(i)  Primary Boot Loader:

Primary boot loader contains partition and that partition contains the code (software program) to boot the system. The size of primary boot loader is 446 Bytes.

(ii) Partition Table:

The partition table is used to store all the information of the created partitions. In linux we can create only 4 primary partitions because the size of partition table is 64 bytes and each primary partition requires 16 byes so 16 x 4 = 64 bytes. Now size of partition size is over, that’s the reason we cannot create more than 4 partitions in linux.

(iii) MBR Validation Check/Magic Number:

If the MBR gets corrupted in this situation Magic Number restore MBR. Its size is 2 Bytes.

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