Set Active Partition
You may have multiple primary partitions (at most 4) on your hard disk drive, active Partition refers to a primary partition which contains boot files of the operating system. After you make a partition as active, the operating system will hence start from that partition. Typically, a disk can have one and only one active partition.
Before you do
Make sure it contains the loader (an operating system tool) or boot files such as “boot.ini”, “ntldr”, “bootmgr” or “BCD” before you mark that partition as active.
If there are other applications running on the partition which you are going to perform, AOMEI Partition Assistant will notice you to close those applications.
Never make a partition which contains no system files as active. Doing so will cause your computer to stop working.
Tips: This operation can ensure absolute security for your data.
To set active partition
Step 1. Launch AOMEI Partition Assistant. Right click on the partition you want to mark as active and select "Advanced" -> "Set Active Partition".
Step 2. Click "OK" in the next step, the change will be presented in the main window.
Step 3. Click "Apply" to open the pending operations as shown in the screenshot below. You will get a reboot warning, click "Proceed" to confirm.
You can't make a logical drive or an extended partition active. Only a primary partition can be set as active.
Your computer can only boot from the main partition which is set active, and there can be only one active partition per physical hard disk drive.