Understanding Basic and Dynamic Disks

When you upgrade to Windows XP or Windows Server 2003, disks with partitions are initialized as basic disks. When you install Windows XP or Windows Server 2003 on a new system with unpartitioned drives, you have the option of initializing the drives as either basic or dynamic.

Basic drives support all the fault-tolerant features found in Microsoft Windows NT 4; however, you can’t create fault-tolerant drive sets using the basic disk type. Because of this, if you want to set up software RAID, you must convert to dynamic disks and then create volumes that use mirroring or striping. The fault-tolerant features and the ability to modify disks without having to restart the computer are the key capabilities that distinguish basic disks from dynamic disks.

Although you can use both basic and dynamic disks on the same computer, disk configuration tasks that you can perform with basic and dynamic disks are different. With basic disks, you work with partitions. This means you can

• Format partitions and mark them as active

• Create and delete primary and extended partitions

• Create and delete logical drives within extended partitions

• Convert from a basic disk to a dynamic disk

With dynamic disks, you work with volumes. This means you can

• Create standard and fault-tolerant volumes

• Remove a mirror from a mirrored volume

• Extend simple or spanned volumes

• Split a volume into two volumes

• Repair mirrored or RAID-5 volumes

• Reactivate a missing or offline disk

• Revert to a basic disk from a dynamic disk (which requires deleting all existing volumes prior to doing so)

With either disk type, you can

• View properties of disks, partitions, and volumes

• Make drive letter assignments

• Configure security and drive sharing

Whether you’re working with basic or dynamic disks, you need to keep in mind three special types of drive sections:

• System  The system partition or volume contains the hardware-specific files needed to load the operating system.

• Boot  The boot partition or volume contains the operating system and its support files. The system and boot partition or volume can be the same.

• Active  The active partition or volume is the drive section from which the computer starts.

Note

You can’t mark an existing dynamic volume as the active volume, but you can convert a basic disk containing the active partition to a dynamic disk. Once the update is complete, the partition becomes a simple volume that’s active.

Setting the Active Partition

On an x86-based computer with the MBR partition style, you can mark a partition as active, which means the partition is the drive section from which the computer starts. You can’t mark dynamic disk volumes as active. When you convert a basic disk containing the active partition to a dynamic disk, this partition becomes a simple volume that’s active automatically.

Note

Before you mark a partition as active, make sure that the necessary startup files are on the primary partition that you want to make the active partition. For Windows Server 2003, these files are Boot.ini, Ntdetect.com, Ntldr, and Bootsect.dos. You might also need Ntbootdd.sys.

Follow these steps to designate the active partition:

1. Invoke DiskPart by typing diskpart at the command prompt.

2. Select the disk that contains the partition you want to make active, such as

   DISKPART> select disk 0

3. List the partitions on the disk by typing list partition at the command prompt.

4. Select the partition you want to work with, such as

   DISKPART> select partition 0

5. Make the selected partition the active partition by typing active at the command prompt.

Caution

The disk and partition numbers used in the steps are arbitrary and meant only to demonstrate the procedure. Make sure you’ve selected the right disk and partition in steps 2 and 4. If you incorrectly mark a partition as active and it does not contain the operating system startup files, your computer might not start.

Changing the Disk Type: Basic to Dynamic or Vice Versa

Windows XP and Windows Server 2003 support both basic and dynamic disk types. At times, you’ll need to convert one disk type to the other and Windows provides the tools you’ll need to do this. When you convert a basic disk to a dynamic disk, partitions are changed to volumes of the appropriate type automatically. You can’t change these volumes back to partitions on a basic disk, however. Instead, you must delete the volumes on the dynamic disk and then change the disk back to a basic disk. Deleting the volumes destroys all the information on the disk.