The active partition is used to host the operating system boot loader. If the partition with the bootloader is no longer active, the operating system will not be able to boot.
Only the main section can be active. The secondary partition or logical drive cannot be active. Only one partition on a physical disk can be active.
If your computer contains multiple physical hard drives, each of them can contain an active partition. In this case, the operating system boots from the physical hard drive that is specified first in the BIOS hard drive priority setting.
How to make a hard drive partition active
1. From the command line
Enter the commands:
Diskpart list disk sel disk 0 list part sel part 1 active
* select the numbers of the required disks and partitions.
In the console it looks like this:
2. Using the Computer Management snap-in.
Typically you have to do this operation by booting from a LiveCD. Because if a partition has become inactive, then it will not be possible to load the operating system from it.
1 Click WIN+R
2 Enter the command
3 Click Enter or OK:
4 In the window Computer management go to Disk management.
5 Right-click on the desired partition and select Make the section active:
6 Click Yes:
3. Using Acronis Disk Director.
Right-click on the desired partition.
Select an item Additionally and click on the item Make active:
Click OK:
Click the button Execute to make changes:
On computers with x86 processors, the MBR partition can be marked as active via the Diskpart command line utility. This means that the computer will start booting from this partition. You cannot mark dynamic disk volumes as active. When you convert a basic disk with an active partition to a dynamic disk, that partition automatically becomes a simple active volume.
To designate a partition as active, follow this procedure.
- Launch DiskPart by entering diskpart on the command line.
- Select the drive containing the partition you want to make active, like this: DISKPART> select disk 0
- List disk partitions with the command list partition.
- Select the required section: DISKPART> select partition 0
- Make the selected partition active by entering the command active.
Changing the disk type in DiskPart
Windows XP and Windows Server 2003 support basic and dynamic disks. Sometimes there is a need to convert one type of drive to another, and Windows provides tools to accomplish this task. When you convert a basic disk to a dynamic disk, the partitions are automatically converted to volumes of the appropriate type. However, you cannot simply convert volumes back to basic disk partitions. First you need to delete the dynamic disk volumes and only then convert it back to basic. Deleting volumes will result in the loss of all information on the disk.
Converting a basic disk to a dynamic one is a simple process, but it does impose some limitations. Before you begin this operation, keep the following considerations in mind.
- Only computers running Windows 2000, Windows XP, or Windows Server 2003 work with dynamic disks. Therefore, if the disk you are converting contains earlier versions of Windows, you will not be able to boot those versions after conversion.
- Disks with MBR partitions must have at least 1 MB of free space at the end of the disk. Otherwise the conversion will not be completed. The Disk Management console and DiskPart reserve this space automatically; however, when using other disk utilities, you must take care of the availability of this free space yourself.
- Disks with GPT partitions must have contiguous, recognized partitions of data. If a GPT disk contains partitions that are not recognized by Windows, such as those created by another operating system, the disk cannot be converted to dynamic.
In addition to the above, the following is true for any type of disk:
- You cannot convert disks with sectors larger than 512 bytes. If larger sectors are used, the disk must be reformatted;
- Dynamic disks cannot be created on laptops or removable media. In this case, the disks can only be basic with primary partitions;
- You cannot convert a disk if the system or boot partition is part of a mirrored, spanned, striped, or RAID-5 volume. You must first undo the overlapping, mirroring, or striping;
- however, you can convert disks with other types of partitions that are part of mirrored, overlapped/or striped, or RAID-5 volumes. These volumes become dynamic volumes of the same type, and you must convert all disks in the set.
Converting a basic disk to dynamic in DiskPart
Converting a basic disk to a dynamic disk is performed in the following sequence.
- Launch DiskPart by entering diskpart on the command line.
- Select the drive to be converted, for example: DISKPART> select disk 0
- Convert the drive by entering the command convert dynamic.
It happens that a certain partition of the hard drive needs to be made active or, on the contrary, inactive. For example, the user has a new hard drive or a new partition has been created on it. And it happens that due to lack of experience they did the wrong thing. This article will tell you how to carry out these operations.
The Windows boot loader is installed on the active disk partition, which begins loading the operating system. If you activate the wrong partition, the operating system simply will not start. Therefore, more experienced users should penetrate these depths.
Activating a hard disk partition can be done in several ways. This article will look at two of them. First, let's look at activating the partition through the Disk Management menu.
The first way to activate a hard disk partition
To start, press the key combination “Win + R”. In the window that appears, enter the command “diskmgmt.msc” and click “OK”.
A window with hard drive partitions will appear. Select the desired section, right-click on it and select “Make section active”.
Voila! The section is active.
The second way to activate a hard disk partition
The second way to activate a hard disk partition is through the command line. You must run the command line with administrator rights. Click “Start” and enter “cmd” in the “Run” line. Right-click on the Command Prompt shortcut and select “Run as administrator.” On the command line we will launch the built-in “Disk part” utility. To do this, we will write several commands in the already running command line. Let's start with the "diskpart" command and press "Enter". The line "DISKPART>" appears.
To select the disk we need, enter the command “sel disk #”. Instead of # we indicate the serial number of the disk we need and see that the disk we need is selected.
Then we need to select the section that needs to be activated. We display a list of partitions with the “list part” command and, similarly to selecting disks, select a partition with the “sel part” command.
Now all we need is to give the “active” command and the partition will be activated.
To deactivate the desired hard disk partition via the command line, you will need to do the same manipulations, with the exception of the last command. Instead of “active” we write “inactive”.
Deactivating a partition through Disk Management is only possible after formatting the partition. And this is not always advisable to do.
Sometimes when reinstalling the Windows operating system or when switching from a newer system to an older one, an error occurs: " An operating system wasn't found. Try disconnecting any drivers that don't contain an operating system"Also, this error may occur due to improper intervention in the hidden boot partition of the hard drive. In this manual, you can find out how to resolve the “An operating system wasn't found" error.
In Windows 7, 8 or 10, the system boots from a hidden partition (reserved by the system). For each of these operating systems, the hidden partition has a different size: in Windows 7 - 100 MB, in Windows 8 - 350 MB, in Windows 10 - 500 MB.
When installing the system, you probably could see these sections.
The hidden partition contains operating system boot files. If for some reason this partition becomes inactive, the operating system will not boot and you will see the error "An operating system wasn"t found. Try disconnecting any drivers that don"t contain an operating system".
To fix this problem you only need to make the section active.
The hidden section should always be the main and active one. This is an ironclad rule, thanks to which the BIOS understands that the download files are located on the specified partition. Let's see what is stored on this hidden partition as an experiment. First, let's go to "Disk Management"
Since I use Windows 7, it is clear that I have 100 MB reserved by the system. If you assign a letter to this hidden partition, it will be displayed in the “Computer” window, provided that the item “display hidden protected system files” is activated in the system settings.
As you can see, this disk contains OS boot files.
Below we will look at two ways by which the error will go away and the system will boot again in normal mode. By the way, all manipulations can be carried out both on Windows 7 and on Windows 8 and Windows 10.
Method 1. How to make a partition active using Acronis Disk Director
First you need to create an Acronis Disk Director boot disk if you don't have one. The image can be downloaded on the Internet and then burned to disk. If you don’t know how to do this, you can read the article. Next, we boot from this media.The hidden section should always be active, as I wrote above, that is, it should be marked with a red flag in the program. As you can see below, the hidden section is inactive,
To fix this, right-click on the section and click on “Mark as active”
For the changes to take effect, click on the button with the “Apply pending operations” checkbox.
After completing the operation, you can see that the partition has become active.
Now all that remains is to restart the computer. If everything is done correctly, the system will boot and you will be taken to your usual Desktop.