How to Set or Mark a Partition as Active in Windows?

How to Set or Mark a Partition as Active in Windows
How to Set or Mark a Partition as Active in Windows

Do you have several operating systems installed on different partitions on your computer? If this is the case, you can modify the active partition in Windows so that the appropriate operating system is loaded when the computer starts up. A dual-boot or multi-boot system is what this is known as.

Changing the active partition is a very advanced procedure, so you probably didn’t need the following explanation! Only alter the active partition if that partition contains an operating system; otherwise, your machine will stop running.

There are a couple of considerations to keep in mind while declaring a partition as active:

  1. Only primary partitions can be converted to active state, neither logical drives or extended partitions.
  2. Each physical hard disc can only have one active partition. Attempting to do so will result in a slew of issues.
  3. You can identify a partition as active on each physical hard drive on your computer, but only the active partition on the first hard disc identified by your BIOS will start the computer. You can modify the order in which hard drives are detected in the BIOS.

In addition to the items listed above, there are a few more things that must be in place for the system to boot. Simply making a partition active does not guarantee that the system will boot correctly.

  1. The operating system must have built a boot sector on the active partition.
  2. The boot loader and boot files for the OS should be on the active partition, and it should know where the OS is on the physical hard drive.
  3. The operating system must be installed in the proper location on the hard drive.

The computer will check for an active partition on the primary partitions first when it starts up. The boot sector, which is at the start of the active partition, will run the boot loader, which understands where the operating system boot files are placed. The operating system will now begin to boot up and run.

Disk Management can be used to create an active partition.

  1. Go to the Control Panel, click System and Maintenance, and then Administrative Tools to access Computer Management.
  2. You can also select Administrative Tools from the Classic View menu. Now, under Storage, select Disk Management.

Another alternative is to right-click on Computer or This PC on your desktop and select Manage. Disk Management can be found in the left-hand menu, as illustrated above. Mark Partition as Active by right-clicking on the primary partition you want to make active.

Using the Command Line to Change the Active Partition

You won’t be able to boot your computer if you made a mistake in Windows and marked the wrong partition as active. If you can’t use Windows to mark a partition as active, you’ll have to use the command line.

Getting to the command line can be difficult depending on your Windows version. To access to the system repair options for Windows XP, Vista, 7, 8, and 10, read my post on restarting Windows in safe mode. Read my post about booting to system recovery options if you’re using Windows 8. Go to Troubleshoot, then Advanced Options, and then Command Prompt once you’ve arrived.

To begin, use a boot disc to enter the command prompt and type diskpart at the prompt.

Set active partition with diskpart

Type list disc at the DiskPart prompt. You’ll see a list of the discs that are currently connected to your computer. Now type choose disc n, where n is the number of the disc. I’d type select disc 0 in my example.

Now that we’ve found the right disc, type list partition to see a list of all the partitions it has. Type choose partition n, where n is the partition number, to select the partition we wish to make active.

We can mark the disc and partition as active now that we’ve selected them by typing the term active and pressing Enter. That concludes our discussion. The partition has now been established.

Most people are familiar with the command FDISK to declare a partition as active, however it is now obsolete. On a modern Windows PC, you should use DISKPART to handle discs and partitions.

MSCONFIG is used to set the Active Partition.

You can also use MSCONFIG to set the active partition in addition to the two techniques listed above. Note that MSCONFIG will not identify partitions on other hard drives, therefore this method only works for primary partitions on the same hard drive. In order to make the other partition active, it must have only Windows installed.

Read my prior guide on how to use MSCONFIG if you’re not familiar with the tool. Navigate to the Boot tab in MSCONFIG.

You’ll notice the operating systems listed, with Current OS; Default OS after the name of the operating system for the active one. After selecting the other operating system, click Set as default.

Other techniques for creating an active partition exist, such as utilizing a Linux live CD, but they are significantly more difficult and rarely essential. You can always utilize a separate computer to construct a bootable USB system recovery disc if the built-in system recovery options don’t allow you to access to the command prompt.

Mark Funk
Mark Funk is an experienced information security specialist who works with enterprises to mature and improve their enterprise security programs. Previously, he worked as a security news reporter.