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What is a Hard Drive Boot Sector?

A common misunderstanding is that because a hard drive is not a boot drive it does not have or need a boot sector, this just isn’t the case. All DOS based (Windows) hard drives have a boot sector. It is often also confused with the MBR (Master Boot Record) which makes things a little more confusing since they use the same word to explain 2 totally different sectors.

The <NAME OF FILESYSTEM> Boot Sector is its official name and is the sector that holds the information on where the master file table or the FAT start on the drive. It also tells us important information like how big this particular partition is and where this partition starts. The really awesome part of the boot sector is that it keeps a back up of itself. The backup can be found at the end of the partition.

Boot sector RAW

Ok so here is a boot sector, we can tell it is the boot sector because it of the NTFS in the upper left and side of the text side of my hex editor. When using a Hex editor/viewer it is also a good idea to make sure you have the 55 AA in the lower right hand corner of the HEX. Most HEX editor have a way for you to Apply and template to a boot sector so that you can view it as something you can understand and change.

boot sector template

This is the boot sector in a more readable format. You can see the important notes like the file system, hidden sectors (often call the offset). You can see the total sectors which gives us the total size of this particular partition if we take that number and divide it by 2097852 (which is how many sectors in 1 gigabyte). Also see that it has the starting MFT cluster, which is important because this is where the MFT starts. We can figure out where that is on the hard drive by taking that number and x by the sectors per cluster and then adding the offset. When I try to explain the boot sector to customers I use the analogy of  a car the MBR is the key that starts everything off but the boot sector is the like the engine it gets you where your going and does all the heavy lifting. I can usually repair a boot sector even when the backup boot sector have been lost with our remote data recovery service. If your hard drive is clicking or not seen by anything, you need hard drive recovery.

Call Toll Free: 1-866-438-6932 if you need help!

3 Responses to “What is a Hard Drive Boot Sector?”

  1. manu January 10, 2012 12:49 am #

    tell me anyone how to create boot sector problem or destroy the hard disk if i forgot the all passwords of the computer.BIOS and main password.

    • Jacqui Best January 24, 2012 5:02 pm #


      Slave the drive into another computer and then use a piece of software like winhex to manually whack the boot sector.

  2. vicente labadia February 21, 2012 12:32 pm #

    add me up maam.. I want to learn more..

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