Basic and Dynamic Disks

When you first install Windows 7, the hard disk on which you install Windows is set up as a basic disk. When you add a brand-new hard disk to your computer, this disk is also recognized as a basic disk. This disk type is the one that has existed ever since the days of MS-DOS. Starting with Windows 2000, Microsoft offered a new type of disk called a dynamic disk. This disk type offers several advantages over the basic disk, including the following:

• You can create specialized disk volumes on a dynamic disk, including spanned, striped, mirrored, and RAID-5 volumes. Basic disks are limited to primary and extended partitions, and logical drives.
• You can work with and upgrade disk volumes on the fly, without the need to reboot your computer.
• You can create an almost unlimited number of volumes on a dynamic disk. A basic disk can hold a total of only four primary partitions, or three primary plus one extended partitions.

Dynamic disks have their disadvantages, however:

• The disk does not contain partitions or logical drives and therefore can't be read by another operating system.
• On a multiboot computer, the disk might not be readable by operating systems other than the one from which the disk was upgraded. You cannot read a dynamic disk using Windows NT or 9x.
• Laptop computers do not support dynamic disks.

Besides a disk type, all disks have one of two partition styles:

• Master Boot Record (MBR): Uses a partition table that describes the location of the partitions on the disk. The first sector of an MBR disk contains the master boot record plus a hidden binary code file that is used for booting the system. This disk style supports volumes of up to 2 terabytes (TB) with up to four primary partitions or three primary partitions plus one extended partition subdivided into any number of logical drives.
• GUID Partition Table (GPT): Uses extensible firmware interface (EFI) to store partition information within each partition and includes redundant primary and backup partition tables to ensure structural integrity. This style is recommended for disks larger than 2 TB in size and for disks used on Itanium-based computers. Not all previous Windows versions can recognize this disk style, however.

When you add a new disk of less than 2 TB in size, it is added as an MBR disk. You can convert an MBR disk to a GPT one using either Disk Management or the DiskPart tool, provided there are no partitions or volumes on the disk. To use Disk Management, right-click it and choose Convert to GPT Disk. To use DiskPart, proceed as follows:

1. Open an administrative command prompt, type DiskPart, and accept the User Account Control (UAC) prompt. You receive the DiskPart command window.
2. Type list disk to get the disk number of the disks on your system.
3. Type select disk n where n is the number of the disk you want to convert.
4. Type convert gpt. DiskPart informs you that it has successfully converted the selected disk to GPT format.

If you want to convert a GPT disk back to MBR, the procedures are the same. You must back up all data and delete all volumes on the disk before performing the conversion. In Disk Management, right-click the disk and choose Convert to MBR Disk. In DiskPart, use the same steps and type convert mbr in the last one.