What should I do after accidentally marking Drive C as active [New]?

If your PC fails to boot after accidentally marking Drive C as active, and you're unsure how to rectify the situation by activating the correct system partition, this article is designed to guide you. In this article, we will explore the consequences of accidentally marking Drive C as active, the importance of the System and Boot partitions, and which partition should actually be active.

First, let's understand what happens when you mark the C drive as active. You will encounter an error message stating "Unable to load MBR" when attempting to boot your computer. The MBR (Master Boot Record) will only load the boot files and initiate the PC startup process if the correct partition containing the boot files is marked as active.

In the next section, we will explore the partitions existing on the PC, their functions, and which one should be activated to rectify such errors.

Which Partition Should Be Activated

Before delving into how to set the system partition as active, let's first understand the concepts of the system partition and the boot partition, as well as their roles in booting your PC. We'll explore their distinctions and functionalities. The system partition is a crucial part of your computer's storage that contains essential system files and components required for the operating system to function. It includes the Windows System32 folder, boot configuration data (BCD), and other vital system files. The system partition doesn't necessarily need to be separate from the boot partition; in many cases, they can be combined into one. The boot partition, on the other hand, refers to the partition that holds the operating system's core files, such as the Windows OS itself. This is where the boot loader, which initiates the process of loading the operating system, is located. When you turn on your PC, the boot loader is responsible for starting the system by loading the necessary files from the boot partition. Now, to differentiate between the two: 1. **System Partition**: Contains system files and components required for the OS to function. 2. **Boot Partition**: Holds the core OS files and the boot loader, initiating the OS loading process. In some cases, the system and boot partitions may be the same, especially in simpler configurations or on smaller storage devices. However, having separate partitions can offer advantages like better organization, easier maintenance, and improved reliability. When setting up a new operating system or dealing with disk management, it's important to ensure that the correct partition is marked as 'active.' The active partition is the one that contains the boot loader, and the BIOS or UEFI firmware will look for it during the boot process. If the system partition is not set as active, your PC may fail to start properly. To set the system partition as active, you can use tools like the Command Prompt in Windows (specifically the `diskpart` utility) or third-party disk management software. Make sure to exercise caution when manipulating partitions, as incorrect actions can lead to data loss or an unbootable system.

In older versions of the OS, both the system partition and the boot partition were contained within the same partition, located on drive C. Starting with Windows 7, these partitions can either be combined or kept separate. For each operating system on your PC, there exists a system and boot partition; if you have multiple OS installations, it's possible to have several system and boot partitions.

Guideline for System Partition and Boot Partition

Therefore, if we install the Windows OS on a never-used hard disk, the System and Boot partitions will be separate. In Disk Management, the partition with System Reserved data (500MB for Windows 10, 350MB for Windows 8, and 100MB for Windows 7) is the system partition, and the C drive is the boot partition, as illustrated in the image.

Now there is a System Reserved partition, and there can be only one system partition on each disk, regardless of how many operating systems are installed. All the boot files for the installed Windows OS will be automatically saved to this system partition with multiple boot partitions on other drives.

In a straightforward manner, the partition that holds boot components such as BOOTMGR and BCD or NTLDR and boot.ini is referred to as a System partition. For a successful Windows OS boot, this System partition must be activated. It can either be located on drive C or exist independently as a System Reserve partition.

If you have multiple Windows operating systems installed on your device, you will have multiple system partitions on a single disk. In this scenario, you need to set the partition corresponding to the desired OS version as active in order to boot your PC.

Now, let's learn about all the files or programs that make up the system and boot partition.

System partition mainly contains:

1. Windows Boot Manager (BOOTMGR) is a component of the boot volume record, responsible for initiating your operating system by executing the winload.exe file. 2. BCD (Boot Configuration Database) is a program that supersedes the boot.ini file. 3. Win RE: The Windows Recovery Environment, referred to as "System" in Disk Management.

Boot partition primarily contains:

As you can see in Disk Management, the boot partition is our C drive on the PC. It contains all the Windows operating system files.

Generally, when you start your computer, it follows a predefined sequence of steps to boot (restart) the operating system (OS) files and power up the device. In this process, the Master Boot Record (MBR) looks for the active system partition on the master hard drive. It then reads this partition, which contains all the necessary files for booting. Afterward, the MBR loads the Boot Manager (BOOTMGR), transferring control to it. The BOOTMGR, in turn, reads the Boot Configuration Data (BCD) store to identify the available boot menu options. Based on user input or default settings, it initiates the winload.exe executable. This component is responsible for loading the appropriate kernel and core device drivers, thus booting the Windows operating system.

Solve the Issue of Accidentally Marking Drive C as Active - 2 Methods

We offer two solutions to assist you with this issue, and you can select the one that best suits your requirements. They are as follows:

Method 1: Resolve Accidentally Marked Drive C as Active Issue with Partition Master Tool

Way 2: Resolve Accidentally Marked Drive C as Active Using Windows Installation Media

To resolve this issue and set the correct system partition as active, follow the two methods outlined below.

Method 1: Resolve Accidentally Marked Drive C as Active Issue with Partition Master Tool

tools Partition Master is a dedicated partition management software that effortlessly handles partitions on hard drives, SSDs, and external disks. It offers the "Set Partition as Active" function. With tools Partition Master, you can swiftly activate the necessary system partition on your PC with just one click, safeguarding your Windows from MBR disk boot failure. Download the tool and follow the guide below to give it a try.

Step 1. Run the partition manager software. On the disk map, right-click the target partition and choose "Advanced".

Step 2. Next, select "Set Active" from the dropdown menu. Click "Yes". Then choose "Execute 1 Task(s)" and click "Apply".

Aside from handling disk partitioning, this utility aids in freeing up hard drive space and managing USBs and external hard drives to enhance your disk performance. Download the software and utilize its user-friendly interface to effortlessly execute complex operations on your hard drives.

Method 2: Resolve Accidentally Marked Drive C as Active Issue Using Windows Installation Media

If you have a bootable CD, DVD, or USB flash drive, you can utilize the Windows Installation Media to address the issue. If you require assistance in creating a bootable CD, DVD, or USB flash drive, refer to the respective articles for detailed instructions.

Step 1: Boot the computer using a bootable Windows Installation media such as a CD, DVD, or USB. While booting, you'll need to access the BIOS settings. Each computer has a different key for entering the BIOS settings, so refer to your computer's documentation or on-screen prompts for the specific key to press.

Step 2: You will be redirected to the installation setup. Select your language and time, and you will then see the following screen. Click on "Repair your Computer."

Step 3: Now Troubleshoot > Advanced Options > Command Prompt. Now enter the following commands one by one and hit Enter after each entry.

1. diskpart
2. list disk
3. select disk 2 (2 refers to the number of the disk you will work on)
4. list partition
5. select partition n (n stands for the number of the correct system partition)
6. active

Once you've executed these commands, restart your computer to check if it boots normally, just as it did before. By the way, you might find the following links useful:

The Ultimate Verdict

If you have accidentally marked Drive C as active, it can lead to booting issues on your computer. To gain a comprehensive understanding of system partitions and learn how to resolve this problem, follow this guide. You can conveniently use the Partition Master tool with a single click to fix the issue, or opt for Method 2 to manually accomplish this through BIOS settings.

Be careful when inputting commands, or data loss might occur. Therefore, using a tool like Partition Master is a safer option since it can set the boot partition without causing any data loss. Download this tool and give it a try; you'll appreciate its benefits.

"What should I do after accidentally marking Drive C as active?" FAQs

Here are some of the most commonly asked questions on this subject. If you have similar inquiries, hopefully, this will be of assistance to you.

1. What happens if I mark the partition as active? If you mark a partition as active, it means that you are designating it as the bootable partition. This is particularly relevant in systems with multiple partitions or operating systems. When a computer starts up, the boot loader looks for an active partition to initiate the boot process. Here's what typically happens: - **Boot Process**: The computer's Basic Input/Output System (BIOS) or Unified Extensible Firmware Interface (UEFI) scans through all the partitions on the hard drive and looks for the active flag. - **Loading Boot Loader**: If it finds an active partition, it loads the boot loader (e.g., GRUB, Bootmgr) located in that partition. The boot loader then manages the process of loading the operating system installed on that partition. - **Potential Issues**: If you have only one operating system, marking the correct partition as active is crucial. If you accidentally mark the wrong partition as active, the computer may not be able to boot correctly. It could lead to a 'No Operating System Found' error or similar issues. - **Multiple OS**: In a multi-boot system, each operating system should ideally have its own boot loader on an active partition. Marking the appropriate partitions as active is necessary for smooth operation. Remember, making changes to partition activation can sometimes require technical knowledge and could potentially cause problems if not done correctly. Always ensure you have a backup before making such changes.

Generally, the active partition is responsible for loading or booting your computer. It contains all the boot and operating system (OS) files and is referred to as a system partition. When you designate it as active, the OS is loaded and initiates the startup process, typically residing on the computer's local disk.

2. How do I mark a drive as active? To mark a drive as active, follow these steps in Windows: 1. **Access Disk Management:** Press `Windows + X` and choose 'Disk Management' from the menu or right-click on the Start button and select 'Disk Management'. 2. **Locate the Drive:** In the Disk Management window, find the drive you want to mark as active. It will usually be labeled with a drive letter (e.g., C:, D:). 3. **Check Drive Status:** Look for the status column next to the drive. If it says "Not Active," the drive is currently not set as the active system partition. 4. **Mark Drive as Active:** Right-click on the partition that contains the operating system (usually the primary partition) and select 'Properties'. In the Partition Properties window, check the box next to "Active" under the "Volume" tab. Click 'OK' to apply the changes. 5. **Warning:** Marking the wrong drive as active can lead to boot issues. Make sure you select the correct partition that contains your operating system. Please note that these instructions are for Windows. Other operating systems have different methods to mark a drive as active. If you're using a different OS, please consult its documentation or support resources.

You can either utilize a professional software utility such as tools Partition Master or perform the task manually using the Command Prompt with the assistance of Windows Installation Media. In this case, it's recommended to opt for the more straightforward method:

Step 1. Download and launch tools Partition Master.

Step 2. Right-click the target hard drive and select "Advanced."

Step 3. Choose "Set Active" and then click "Execute Task."

3. Should the C drive be an active partition?

Sometimes it's the System Reserved partition, and other times it's the C drive. You can designate it as the active partition. Setting the system partition as active is necessary for booting the computer. This dependency lies with the drive that contains the system partition.