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Mark a partition as active (32-bit only)

  • Article

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

To mark a partition as active (32-bit only)

  • Using the Windows interface

  • Using a command line

Using the Windows interface

  1. Open Computer Management (Local).

  2. In the console tree, click Computer Management (Local), click Storage, and then click Disk Management.

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

Notes

  • To perform this procedure on a local computer, you must be a member of the Backup Operators group or Administrators group on the local computer, or you must have been delegated the appropriate authority. To perform this procedure remotely, you must be a member of the Backup Operators group or Administrators group on the remote computer. If the computer is joined to a domain, members of the Domain Admins group might be able to perform this procedure. As a security best practice, consider using Run as to perform this procedure. For more information, see Default local groups, Default groups, and Using Run as.

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

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

  • 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.

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

  • 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 partitionn

    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.
Value Description

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.

Notes

  • To perform this procedure on a local computer, you must be a member of the Backup Operators group, Administrators group, or you must have been delegated the appropriate authority. If the computer is joined to a domain, members of the Domain Admins group might be able to perform this procedure. As a security best practice, consider using Run as to perform this procedure. For more information, see Default local groups, Default groups, and Using Run as.

  • To open a command prompt, click Start, point to All programs, point to Accessories, and then click Command prompt.

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

  • 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.

  • 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.

Information about functional differences

  • Your server might function differently based on the version and edition of the operating system that is installed, your account permissions, and your menu settings. For more information, see Viewing Help on the Web.

See Also

Concepts

Change a basic disk into a dynamic disk
Partition styles
Working with MMC console files
DiskPart