Concept of Boot Sector

Boot Sector is that section of the hard disk or any other storage device which holds device code to be loaded into RAM by a system’s built in firmware. Boot sector is the most significant part of the hard disk which allows booting process of a computer. It is having a length of 512 bytes. It simply instructs the computer on how to boot any storage device. Boot Sector are divided into two parts: i) MBR, i.e., Master Boot Record, ii) Volume Boot Record.

Hard drives are made up of number of sectors and the boot sector is the most important sector in them. The boot sector is located as first sector in each partition of hard disk drive. It helps to load an operating system on drive. Boot sector exist in the internal part of drive and this is the only reason that it may easily get affected by viruses.

How Boot Sector Works?

When we start a computer, the very first thing that occurs is it send a signal to a motherboard which in return send a power supply to a computer to start. After supplying the power to each device, it sends a signal called “POWER OK” to BIOS (Basic Input/Output System) which is in the motherboard.

Once the BIOS receive this “OK” Signal, it starts the booting process by first initializing the “Power on Self-Test(POST) process.  The work of a POST is to check whether all the devices are getting the appropriate amount of power supply or not and then check for the memory status whether it is corrupted or not.  Then it initializes each devices and the handover the control to the BIOS for further Booting Process.

Now, only the final step of booting is left. For this, the BIOS first search 512 bytes of image known as “Master Boot Record(MBR)” or boot sector from the floppy disk or hard disk which is used for booting. The priority is set by the user in the BIOS setting.

On finding the boot sector, BIOS loads the image in memory and execute it. If a valid boot sector is not found, BIOS remain searching in the next drive until it gets a valid boot sector. If a BIOS is unable to find a valid sector, it stops the execution and gives an error message “Disk Boot Failure”.

What are Boot Sector Errors?

A sector should have a specific disk signature which makes it highlighted as the boot sector in BIOS. A boot sector signature should be 0x55AA and is contained in its last two bytes of information. If, somehow, the boot sector signature gets corrupted or changed, then error will take place. BIOS will not recognize the boot sector and also not able to perform further commands.

Following Errors will represent the Issue with Boot Sector: 

• Invalid Partition Table

• Boot Manager not found

• Missing Operating System

• A Disk read error occurred

• Error loading operating system

How to Repair Damaged Boot Sector Windows 7?

Use Window Recovery to troubleshoot the Windows bootable issue. For this, you just get a startup repair option in the system recovery window. If this doesn’t help you out, then use Bootrec.exe tool to repair MBR or boot sector or boot configuration data store.

Learn How to Run Bootrec.exe tool?

Assuming, you are a Windows 7 user. Now just put the Window 7 media in the DVD drive and then start your system.

1. Now press a key when you are prompted

2. Select a language, a currency, a time, an input method, and then click Next.

3. Now click on repair your computer

4. Select the Operating system that you want to repair and then click next.

5. Click Command Prompt in the System Recovery Options box.

6. Then type Bootrec.exe and then enter.

Bootrec.exe tool will give you various options to repair Bootsector of the hard disk such as /FixMBR, /FixBoot, /ScanOS, /RebuildBCD. You can choose any of them as per the requirement to repair your hard drive boot sector.

Have you lost your data After Repairing Boot Sector?

Most of the time it happens, when after completing the Boot sector repairing process, user lost their precious data from hard drive. This is the most painful situation that ever faced by any computer user. To overcome from this problematic situation user should take help from professional data Recovery Company instead of using any manual recovery options because manual recovery can make the situation worst.  User can download any free data recovery software from a trustworthy site like Stellar Phoenix to recover their lost data from hard disk drive.