The Mark Partition as Active option is greyed out when the partition that you are trying to mark as active is not a primary partition. In addition, if you are using UEFI mode on your computer, you will find the mentioned option greyed out since it is no longer needed.
A partition needs to be marked active when you are trying to indicate to the computer firmware to boot from it. This means the partition must have a bootable source in order to be marked active. In this article, we will be explaining why the mark partition as active option in the Disk Management tool is greyed out and provide an alternative that you can use instead.
Why is the Mark Partition as Active Option Greyed Out?
When you encounter a greyed-out Mark Partition as Active option in the Disk Management utility, it is mainly due to two factors. First, the partition that you are trying to mark as active is not a primary partition.
A primary partition is usually where your operating system is installed. Windows requires a primary partition for installation, which enables it to be set as the active partition as well. Thus, if the partition you are trying to mark active is a logical partition instead of a primary partition, the option in question will be greyed out.
Secondly, the boot mode that you are using on your computer can also cause the greyed-out behaviour. This is because, typically in Basic Input/Output System (BIOS), you need an active partition which separates it from others. This tells the firmware that the partition contains bootable media and acts as a boot source.
However, modern boot modes, like UEFI, do not require an active partition. This is because the system always boots into the EFI System Partition (ESP) and so the active flag is always ignored. As such, if you are in UEFI mode, the option in question will naturally be greyed out since it serves no purpose.
Another thing to keep in mind is that you can only have one active partition per hard disk. Since this partition is the one the system will be booting into, you cannot have multiple active partitions on a single hard disk because it can lead to confusion as to which partition to boot into.
Use DiskPart to Mark Partition as Active
With the Mark Partition as Active option in the Disk Management tool greyed out, you would think there is no way around the issue. However, that is far from the truth as you can use a different utility in Windows that allows you to manage the drives on your computer as well.
DiskPart is a command-line alternative to Disk Management that allows you to do the same things you would be able to do with the Disk Management utility at the cost of using a command-line interface.
If you have to set a partition as active on a different drive on your computer, you can use the DiskPart utility to do the job. The process is quite simple and it only involves navigating through a few commands to achieve the target.
Follow the instructions below to mark a partition as active with the help of DiskPart:
- First, open the command prompt by searching for it in the Start Menu.
- In the command prompt window, type in diskpart and hit Enter.
- Click Yes on the follow-up User Account Control dialog box.
- Once the DiskPart utility is open, type in the following command:
- This will list all of the disks installed on your computer.
- To select a disk, enter the following command:
select disk X
- Make sure to replace X with the number of the disk.
- After that, list the partitions in the disk with the following command:
- Select the partition that you wish to mark active with the following command:
select part X
- Replace X with the partition number and ensure it is a Primary partition.
- Finally, type in the following command to mark it as active:
- Once you do that, you can exit the diskpart utility. Either close the window or type in exit at the prompt.
With that, you are done. The selected partition will now be marked active in the selected disk.