Windows 7 / Getting Started

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Using and Converting Basic and Dynamic Disks

Basic disks and dynamic disks are managed in different ways. For basic disks, you use primary and extended partitions. Extended partitions can contain logical drives. Dynamic disks allow you to combine disks to create spanned volumes, to mirror disks to create mirrored volumes, and to stripe disks using RAID 0 to create striped volumes. You can also create RAID-5 volumes for high reliability on dynamic disks.

You can change storage types from basic to dynamic and from dynamic to basic. When you convert a basic disk to a dynamic disk, existing partitions are changed to volumes of the appropriate type automatically and existing data is not lost. Converting a dynamic disk to a basic disk isn't so easy and can't be done without taking some drastic measures. You must delete the volumes on the dynamic disk before you can change the disk back to a basic disk. Deleting the volumes destroys all the information they contain, and the only way to get it back is to restore the data from backup.

You should consider a number of things when you want to change the storage type from basic to dynamic. To be converted successfully, an MBR disk must have 1 megabyte (MB) of free space at the end of the disk. This space is used for the dynamic disk database, which tracks volume information. Without this free space at the end of the disk, the conversion will fail. Because both Disk Management and DiskPart reserve this space automatically, primarily only if you've used third-party disk management utilities will you need to be concerned about whether this space is available. However, if the disk was partitioned using a much older version of the Windows operating system or a third-party utlity, this space might not be available either.

A GPT disk must have contiguous, recognized data partitions to be converted successfully. If the GPT disk contains partitions that the Windows operating system doesn't recognize, such as those created by another operating system, you won't be able to convert a basic disk to a dynamic disk. When you convert a GPT disk, the Windows operating system creates LDM Metadata and LDM Data partitions. GPT disks that are dynamic will store the dynamic disk database in the LDM partitions instead of out at the end of the drive like on an MBR disk

With either type of disk, you can't convert drives that use sector sizes larger than 512 bytes. If the disk has large sector sizes, you must reformat the disk before converting. You can't convert a disk if the system or boot partition uses software RAID. You must stop using the software RAID before you convert the disk.

Both Disk Management and DiskPart can be used to change the storage type.

Using Disk Management to Convert a Basic Disk to a Dynamic Disk To use Disk Management to convert a basic disk to a dynamic disk, start Computer Management from the Administrative Tools menu or by typing compmgmt.msc at the command line, expand the Storage node, and then select Disk Management. In Disk Management, right-click a basic disk that you want to convert, either in Disk List view or in the left pane of Graphical View, and select Convert To Dynamic Disk.

In the Convert To Dynamic Disk dialog box, select the disks you want to convert. If you're converting disks that will be used in a RAID volume, be sure to select all the basic disks in the set because they must be converted together. Click OK when you're ready to continue.

Next, the Disks To Convert dialog box shows the disks you're converting along with details of the disk contents. To see the drive letters and mount points that are associated with a disk, select the disk in the Disks list, and then click Details. If a disk cannot be converted for some reason, the Will Convert column will show No and the Disk Contents column will provide a reason. You must correct whatever problem is noted before you can convert the disk.

When you're ready to start the conversion, click Convert. Disk Management will then warn you that after you finish the conversion you won't be able to boot previous versions of the Windows operating system from volumes on the selected disks. Click Yes to continue. If a selected drive contains the boot partition, system partition, or a partition in use, you'll see another warning telling you that the computer will need to be rebooted to complete the conversion process.

Using DiskPart to Convert a Basic Disk to a Dynamic Disk To use DiskPart to convert a basic disk to a dynamic disk, invoke DiskPart by typing diskpart, and then select the disk you want to convert. For example, if you want to convert disk 2, type select disk 2. After the disk is selected, you can convert it from basic to dynamic by typing convert dynamic.

Using Disk Management to Change a Dynamic Disk Back to a Basic Disk To use Disk Management to change a dynamic disk back to a basic disk, you must first delete all dynamic volumes on the disk. Then right-click the disk, and select Convert To Basic Disk. This changes the dynamic disk to a basic disk, and you can then create new partitions and logical drives on the disk.

Using DiskPart to Convert a Dynamic Disk to a Basic Disk To use DiskPart to convert a basic disk to a dynamic disk, invoke DiskPart by typing diskpart, and then select the disk you want to convert. For example, if you want to convert disk 2, type select disk 2. If there are any existing volumes on the disk, you must delete them. You can do this by typing clean. However, be sure to move any data the disk contains to another disk prior to deleting the disk volumes.

After you delete all the volumes on the disk, you can convert the disk from dynamic to basic by typing convert basic. This changes the dynamic disk to a basic disk, and you can then create new partitions and logical drives on the disk.