diskpart.exe howto

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You can use Diskpart to convert a basic disk to a dynamic disk. The basic disk can either be empty or contain either primary partitions or logical drives. The basic disk can be a data disk or system or boot drive. 

The basic disk cannot have fault-tolerant disk driver (FtDisk) sets such as stripes or mirrors. To convert basic disks that have FtDisk driver sets, use Disk Management on Windows 2000 or convert the disk before you upgrade to Windows XP.

You can use Diskpart to convert a dynamic disk to a basic disk. You must delete any dynamic volumes before the conversion process. It is not recommended that you delete partitions on a dynamic disk except in emergency situations. 

It is recommended that you delete all volumes on the drive, and then convert the disk to basic. You must delete all dynamic data partitions.

 Also, never mix the basic primary and dynamic partitions on the same drive. If you do so, the computer may be unable to restart. 

You can use Diskpart to create a partition at an explicit disk offset. The Disk Management snap-in places the partition at the end of any occupied area or on the first sufficiently large area. On master boot record (MBR) disks, the partition offset and the size are rounded to preserve the required cylinder alignment. Offsets are rounded to the closest valid value, and the size is always rounded up to the next valid value. Diskpart does not assign a drive letter to a newly created partition. 

Use the assign command to assign either a mount point or a drive letter.

Diskpart follows the same policy as the snap-in. Dynamic disks can only be created on fixed disks. You cannot convert removable disks, such as 1394 or universal serial bus (USB) drives, to dynamic disks.

Diskpart permits certain partition deletion operations that are blocked by the snap-in. For example, you can use Diskpart to delete MBR OEM partitions. However, these partitions often contain files that are important to the platform operation. Diskpart blocks the deletion of the current system, boot, or paging volumes and partitions.

 Also, Diskpart blocks deletion of the partitions that underlie dynamic disks.

You cannot use Diskpart to create a partition on removable media. Windows supports at most one MBR partition on removable media. If the media is manufactured with an MBR, that MBR cannot be altered, but the MBR is followed even if multiple partitions or logical drives are configured. If the media is manufactured without an MBR, the media is treated as a "superfloppy" and no partition structure is written to the media.

The drive letter for a removable drive is associated with the drive, and not with the media. You can use Diskpart to change the drive letter.

Diskpart causes disk signatures, GUID partition table (GPT) disk globally unique identifiers (GUIDs), and GPT partition GUIDs to be generated. You cannot explicitly set these items by using Diskpart.

The Diskpart utility (like the snap-in) includes support for the new Itanium disk partition scheme called GPT. You cannot use GPT disks on any x86-based Windows XP-based or Windows 2000-based computers. Diskpart enables the conversion of GPT partitioning to MBR partitioning only for empty disks.

You can use Diskpart to delete missing dynamic disks. Dynamic disks contain a shared database; all of the dynamic disks on a computer have knowledge of all other dynamic disks on that computer. When dynamic disks are moved, the original computer considers theses disks as "missing". 

Drive letters are not automatically assigned when you use Diskpart. To ensure that a given partition or volume has a drive letter, you must explicitly assign a drive letter. You can either assign the drive letter or allow the next available drive letter to be allocated.

Setting Focus

Most Diskpart commands operate on a specific target disk, partition, or volume. The targeted object has "focus." Focus simplifies the common configuration task in which you create multiple partitions on the same disk. An object is put into focus by the select command. All Commands except for list, rem, exit, or help require focus. 

Use the select command to explicitly change the focus. To implicitly change the focus, use a command such as create. You must set the disk focus before you manage a basic disk. On basic disks, the partition focus and volume focus are the same. If you change the focus on one item, you change the focus on the other. On dynamic volumes, only the volume focus is important because the previous partition focus is always lost and the disk focus is only important for simple volumes. 

Consider the following examples of a computer that has two disks:

• Each disk contains two primary partitions. The first disk contains the C and D partitions; the second disk contains the E and F partitions. You must set the disk focus to disk 1 before you set the partition focus to either the C or D partitions. You can set the volume focus to either the C, D, E, or F partitions at any time. In this example, if you set the volume focus to the C or D partition, the disk focus does not change; however, if you set the volume focus to the E or F partitions, the disk focus may be moved to the other disk.
• Each disk is dynamic and contains a simple volume and free space. The first disk contains the C partition, and the second disk contains the E partitions. You must set the disk focus before you add a simple volume to the first disk. To extend the C partition, you need to set only the volume focus. Similarly, to add a mirror to the E partition, you need to set only the volume focus to the E partition. If you create a simple volume or extend an existing volume onto the same disk, you do not change the disk focus. If you add a mirror, create a stripe set, or extend an existing volume onto a different disk, you can cause the disk focus to be lost.

Commands to Set Focus

select

Use the select command to set the focus to the specified target. To obtain a list of focus types, leave the Type field blank. If you do not specify an identification (ID) number, the current focus object is displayed.

select disk[=n]

Use the select disk command to set the focus to the disk that has the specified Windows NT disk number. If you do not specify a disk number, the command displays the current in-focus disk.

select partition[=n/l]

Use the select partition command to set the focus to the specified partition. If you do not specify a partition, the current in-focus partition is displayed.

On basic disks, you can specify the partition by either index, drive letter, or mount point. You can only specify the partition by index on dynamic disks.

select volume[=n/l]

Use the select volume command to set the focus to the specified volume. If you do not specify a volume, the command displays the current in-focus volume.

You can specify the volume by either index, drive letter, or mount point path. On a basic disk, if you select a volume, the corresponding partition is put in focus.

Commands to Display Disk Configuration

Use the list command to display a summary. To display more information, set the focus, and then use the detail command.

detail disk

detail volumen

detail partition

list disk

list volumen

list partition

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active 

Use the active command to set the current in-focus partition to "active." This setting informs the firmware that the partition is a valid system partition. Diskpart does not validate the partition contents. 

NOTE: If you use this command, the computer may be unable to restart. ?????

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assign [[letter=l]/[mount=path]] [noerr]

Use the assign command to assign a letter or mount point to the current in-focus partition. If you do not specify a drive letter, the next available drive letter is assigned. If the letter or mount point is already in use, an error is generated unless you use the noerr parameter.

You can use this command to change the drive letter that is associated with a removable drive.

The drive letter assignment is blocked on the system, boot, or paging volumes. This command cannot be used to assign a drive letter to an OEM partition or any GPT partition, other than the Msdata partition.

create partition primary [size=n] [offset=n] [id=byte/guid] [noerr]

Use the create partition primary command to create a primary partition of length size and a starting address offset on the current drive.

If an ID byte is not specified on an MBR disk, this command creates a partition with type "0x6." You can use the ID parameter to specify the partition type. There is no validity or other checking of the ID byte.

If you do not specify an ID GUID on a GPT disk, this command creates an Msdata partition. You can use the ID parameter to specify any GUID. There is no validity, duplication, or other checking of the GUID. The partition instance GUID is automatically generated.

MBR and GPT partitions are created so that Windows does not automatically allocate drive letters. You must explicitly assign a drive letter.

create partition extended [size=n] [offset=n] [noerr]

Use the create partition extended command to create an extended partition of length size and starting address offset on the current drive. The drive must be an MBR disk.

After the partition is created, the new extended partition gains the focus. You can create only one extended partition. You can create logical drives only after you create an extended partition.

create partition logical [size=n] [offset=n] [noerr]

Use the create partition logical command to create a logical drive of length size and starting address offset in an existing extended partition on the current disk. The drive must be an MBR disk. 

If an offset is not listed, the logical drive is placed in the first unoccupied contiguous disk extent in the extended partition that is large enough. If a size is not listed, the partition may be extended to occupy the entire extended partition.

After you create the partition, the logical drive gains the partition focus.

create partition msr [size=n] [offset=n] [noerr]

(microsoft reserved)

Microsoft requires an MSR on every GPT disk, and recommends it to be created as the disk is initially partitioned. It should be located after the EFI System Partition (ESP) and any OEM service partitions, but—most importantly—the first data partition must follow it. Initial size of MSR is 32MB on disks smaller than 16 GB, or 128 MB on other disks, although it may later automatically shrink on behalf of other partitions, for example during the conversion from basic disk to dynamic disk

The create partition msr command is the equivalent of creating the partition with the MSR GUID E3C9E316-0B5C-4DB8-817D-F92DF00215AE.

create partition esp [size=n] [offset=n] [noerr]

The create partition esp command is the equivalent of creating the partition with ESP GUID C12A7328-F81F-11D2-BA4B-00A0C93EC93B.

delete partition [noerr] [override]

Use the delete partition command to delete the current in-focus partition.

Diskpart blocks the deletion of the current system, boot, or paging volume. To delete either an ESP, MSR, or a known OEM partition, you must specify the override parameter.

extend [size=n][noerr] 

Use the extend command to cause the current in-focus volume to be extended into contiguous unallocated space. The unallocated space must follow (it must be of higher sector offset than) the in-focus partition. The intended use of this command is to grow an existing basic data partition into newly created space on an extended hardware RAID logical unit number (LUN).

If the partition had been previously formatted with the NTFS file system, the file system is automatically extended to occupy the larger partition, and data loss does not occur. If the partition had been previously formatted with any file system format other than NTFS, the command is unsuccessful and does not change the partition.

Diskpart blocks the extension of only the current system or boot partition.

remove [[letter=l]/[mount=path]/[all]] [noerr]

Use the remove command to remove a letter or mount point from the current in-focus partition. If you specify the all parameter, all of the current drive letters and mount points are removed. If you do not specify a letter or mount point, the drive letter is removed.

Use this command to change the drive letter that is associated with a removable drive.

The drive letter removal is blocked on the system, boot, or paging volumes. You cannot use this command to remove a drive letter to an OEM partition, any GPT partition with an unrecognized GUID, or any of the special non-data, GPT partitions, such as, the ESP partition.

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Commands to Manage Dynamic Disks

NOTE: Diskpart forces the creation of an MSR partition on any empty disk when that disk is converted to a dynamic or GPT disk.