The active partition is that (fundamental) partition on the PC that contains the operating system (Windows). It is therefore a primary partition on the hard drive without which the operating system will not boot.It is possible to have only one primary partition as the active partition on each hard disk. It is absolutely not possible to have more than one active partition.
Why make a partition active?
When the PC is turned on and started, the BIOS immediately searches for the active partition among the primary partitions. This partition has a boot sector that allows you to run the boot loader (function of the operating system) to start the operating system. Only in this way can the computer boot up smoothly and take you to the Windows desktop screen.
That’s why it’s important to set a partition as active: if you don’t, Windows won’t be able to boot. In addition, the following 3 things must be considered for the computer to work properly:
- The active partition must contain a boot sector
- The active partition must contain the boot loader and boot files for the operating system
- The operating system must be placed in the correct place on the hard drive.
How to set or change active partition
Before seeing how to set or modify an active partition, it is necessary to specify that on an MBR hard disk you can have up to 4 primary partitions but only one of the 4 primary partitions can be set as an active partition . Since there can be 4 primary partitions with 4 different operating systems installed, the one that is marked active is the one that is used for booting and must contain all the files needed for booting the operating system. – boot loader (e.g. ntldr or bootmgr) to load operating systems from a disk.
If you can have up to 4 primary partitions on an MBR disk, there is no concept of primary or logical on a GPT disk, so there is no primary partition limitation.
To set a primary partition as active you can use the free Windows Disk Management tool .
Type “disk management” in the Windows search box and click on the result that appears. The following Disk Management window will open:
At this point, right-click the partition you want to make “active” and click on the option ” Mark as active partition ”
As you can see from the figure above, however, there are cases in which the item “ mark partition as active ” is grayed out and cannot be selected . This happens if there is no primary partition or if you already have an active partition on the disk.
To solve this problem and to be able to set up and change the active partition of your PC in a simpler and more intuitive way, we recommend that you use a professional software such as Partition Assistant . Thanks to this program, if there is no primary partition on the disk you can first create it (by converting a logical partition to primary) and then mark it as the primary partition. Here are the two possible scenarios.
Scenario n. 1: There is no primary partition
If there is no primary partition on the disk, with Partition Assistant you can easily create it by converting a logical partition to a primary partition and then you can set it as the active partition. Here are the steps to follow:
- First download and install Partition assistant on your Windows PC
- In the main program screen select (by clicking with the right mouse button) the logical partition you want to convert to primary and in the drop-down menu that opens select Advanced -> Convert to Primary.
Convert to Primary
- Click OK to confirm and to apply, click Apply at the top
Now that you have the primary partition you can set it as active with these simple steps:
- A) Right click on the primary partition and select Advanced -> Set Active Partition .
Mark a Partition as Active
- Click OK and finally click the Apply button at the top . At this point you will have an active partition on the disk
Scenario # 2: Change a partition that is set active by mistake
Here’s how to change and set the correct primary partition as active:
- Right-click the partition you want to mark as active and select Advanced -> Set Active Partition .
Mark a Partition as Active
2.Click OK and then Apply at the top . This way you will go to fix and set set the correct partition as active.
