To mark a partition as active

Using the Windows interface

1.

Open Computer Management (Local) 

2.

In the console tree, click Disk Management.

Where?

Computer Management (Local) > Storage > Disk Management

3.

Right-click the primary partition you want to mark as active, and then click Mark Partition as Active.

Note

To open Computer Management, click Start, and then click Control Panel. Click Performance and Maintenance, click Administrative Tools, and then double-click Computer Management

You must be logged on as an administrator or a member of the Administrators group in order to complete this procedure. If your computer is connected to a network, network policy settings may also prevent you from completing this procedure. 

In the list and graphical views, the system, active, and boot partitions are marked as System, Active, or Boot, respectively.

You cannot mark a logical drive as active.

You can only mark a partition as active on a master boot record (MBR) disk.

A computer can only have one active partition per disk.

Changing or deleting an active partition might cause your computer not to start.

The names commonly used for partitions containing the startup and operating system files are system and boot partitions, respectively.

The system partition must be a primary partition that has been marked as active for startup purposes and must be located on the disk that the computer accesses when starting up the system. There can be only one active system partition on a disk at a time. You can have multiple basic disks and each can have one active partition. However the computer will only start from one specific disk. If you want to use another operating system, you must first mark its system partition as active before restarting the computer.

The system partition can never be part of a striped volume, spanned volume, or RAID-5 volume 

You cannot mark an existing dynamic volume as active. However, you can convert a basic disk containing the active partition to a dynamic disk. Once the disk is converted, the partition becomes a simple volume that is active. If the active partition is not the current system or boot partition it becomes a simple volume and loses its entry in the partition table, so it can no longer be active.

Using a command line

1.

Open Command Prompt

2.

Type:

diskpart

3.

At the DISKPART prompt, type:

list partition

Make note of the number of the partition that you want to mark as active.

4.

At the DISKPART prompt, type:

select partition n

Select the partition, n, you want to mark as active.

5.

At the DISKPART prompt, type:

active

 Important

DiskPart verifies only that the partition is capable of containing an operating system's startup files. DiskPart does not check the contents of the partition. If you mistakenly mark a partition as "active" and it does not contain the operating system's startup files, your computer might not start.

ValueDescription

list partition

Displays the partitions listed in the partition table of the current disk.

select partition

Selects the specified partition and gives it focus. If no partition is specified, the select command lists the current partition with focus.

active

On basic disks, marks the partition with focus as active. This informs the basic input/output system (BIOS) or Extensible Firmware Interface (EFI) that the partition or volume is a valid system partition or system volume Only partitions can be marked as active.

Note

To open command prompt, click Start, point to All Programs, point to Accessories, and then click Command Prompt

You must be logged on as an administrator or a member of the Administrators group in order to complete this procedure. If your computer is connected to a network, network policy settings may also prevent you from completing this procedure. 

You cannot mark a logical drive as active.

You can only mark a partition as active on a master boot record (MBR) disk.

A computer can only have one active partition per disk.

Changing or deleting an active partition might cause your computer not to start.

The names commonly used for partitions containing the startup and operating system files are system and boot partitions, respectively.

The system partition must be a primary partition that has been marked as active for startup purposes and must be located on the disk that the computer accesses when starting up the system. There can be only one active system partition on a disk at a time. You can have multiple basic disks and each can have one active partition. However the computer will only start from one specific disk. If you want to use another operating system, you must first mark its system partition as active before restarting the computer.

The system partition can never be part of a striped volume, spanned volume, or RAID-5 volume 

You cannot mark an existing dynamic volume as active. However, you can convert a basic disk containing the active partition to a dynamic disk. Once the disk is converted, the partition becomes a simple volume that is active. If the active partition is not the current system or boot partition it becomes a simple volume and loses its entry in the partition table, so it can no longer be active.

For more information about DiskPart, see Related Topics.

Related Topics

Storage types and partition styles

Change a basic disk into a dynamic disk



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