Locating MBR (Master Boot Record)


I am going to show you how to find a location of the MBR on a standard Linux Core drive. Core drive means the primary drive where the Operating System is located. For an IDE or SCSI drive, just type cfdisk -P rst /dev/device_drive (ie, hda) where r equals RAW, s equals SECTORS, and t equals TABLE. This tool provides a look at a clean drive.

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Just typing cfdisk /dev/device_drive (in my case hda) gives me a visual layout of my partitions.

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Bytes 1FE and 1FF with value “55 AA” are defined as the signature bytes or standard word. These values define the end of the partition table and MBR. In this example, we cannot determine the exact starting point of the partition table without first determining the location of the signature bytes and counting backward.

The MBR contains two critical pieces of information: bootloader and partition table. Byte 01BE defines the start point of a partition table, though byte 0 defines the starting point of the MBR. In both cases, everything ends at byte 1FF.



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