Why does Windows Partition Manager leaves 8 MB free space at the end of the Disk

The Windows Partition Manager leaves about 8 MB of unallocated disk space at the end of the disk. This space is reserved by Setup in case you later want to upgrade the Basic Disk to a Dynamic Disk. Dynamic disk information is saved at the end of the disk. The amount that is reserved is a minimum of one cylinder, or 1MB, whichever is greater. One cylinder can be up to 8MB, depending on drive geometry and translation.


Basic Disk Storage

Basic storage uses normal partition tables supported by MS-DOS, Microsoft Windows 95, Microsoft Windows 98, Microsoft Windows Millennium Edition (Me), Microsoft Windows NT, Microsoft Windows 2000, and Windows XP. A disk initialized for basic storage is called a basicdisk. A basic disk contains basic volumes, such as primary partitions, extended partitions, and logical drives. 

Additionally, basic volumes include multidisk volumes that are created by using Windows NT 4.0 or earlier, such as volume sets, stripe sets, mirror sets, and stripe sets with parity. Windows XP does not support these multidisk basic volumes. Any volume sets, stripe sets, mirror sets, or stripe sets with parity must be backed up and deleted or converted to dynamic disks before you install Windows XP Professional.

Dynamic Disk Storage

Dynamic storage is supported in Windows 2000 and Windows XP Professional. A disk initialized for dynamic storage is called a dynamic disk. A dynamic disk contains dynamic volumes, such as simple volumes, spanned volumes, striped volumes, mirrored volumes, and RAID-5 volumes. 

Not every Operating System (OS) supports Dynamic disks. Dynamic disks are only supported by Windows XP, Vista Ultimate, Vista Enterprise and Windows 7. Windows XP Home Edition does not support dynamic disks.


NOTE: Dynamic disks are not supported on portable computers or on Windows XP Home Edition-based computers. 

You cannot create mirrored volumes or RAID-5 volumes on Windows XP Home Edition, Windows XP Professional, or Windows XP 64-Bit Edition-based computers. However, you can use a Windows XP Professional-based computer to create a mirrored or RAID-5 volume on remote computers that are running Windows 2000 Server, Windows 2000 Advanced Server, or Windows 2000 Datacenter Server. You must have administrative privileges on the remote computer to do this.

Storage types are separate from the file system type. A basic or dynamic disk can contain any combination of FAT16, FAT32, or NTFS partitions or volumes. 

A disk system can contain any combination of storage types. However, all volumes on the same disk must use the same storage type.

General Information

• On a basic disk, a partition is a portion of the disk that functions as a physically separate unit. On a dynamic disk, storage is divided into volumes instead of partitions.
• Storage types are separate from the file system type; a basic or dynamic disk can contain any combination of FAT16, FAT32, and NTFS partitions or volumes.
• Windows XP Professional accommodates both basic and dynamic storage. A disk system can contain any combination of storage types. However, all partitions or volumes on the same disk must use the same storage type (Basic or Dynamic).

How to convert a Basic Disk into Dynamic Disk

General Notes

Before you change a basic disk to a dynamic disk, note these items:

• You must have at least 1 megabyte (MB) of free space on any master boot record (MBR) disk that you want to convert. This space is automatically reserved when the partition or volume is created in Microsoft Windows 2000 or Windows XP Professional. However, it may not be available on partitions or volumes that are created in other operating systems.
• When you convert to a dynamic disk, the existing partitions or logical drives on the basic disk are converted to simple volumes on the dynamic disk.
• After you convert to a dynamic disk, the dynamic volumes cannot be changed back to partitions. You must first delete all dynamic volumes on the disk, and then convert the dynamic disk back to a basic disk. If you want to keep your data, you must first back up or move the data to another volume.
• After you convert to a dynamic disk, local access to the dynamic disk is limited to Windows XP Professional and Windows 2000.
• If your disk contains multiple installations of Windows XP Professional or Windows 2000, do not convert to a dynamic disk. The conversion operation removes partition entries for all partitions on the disk with the exception of the system and boot volumes for the current operating system.
• Dynamic disks are not supported on portable computers or Microsoft Windows XP Home Edition.

Before you change a dynamic disk back to a basic disk, note that all existing volumes must be deleted from the disk before you can convert it back to a basic disk. If you want to keep your data, back up the data, or move your data to another volume. 

How to Convert a Basic Disk to a Dynamic Disk

To convert a basic disk to a dynamic disk:

1. Log on as Administrator or as a member of the Administrators group.
2. Click Start, and then click Control Panel.
3. Click Performance and Maintenance, click Administrative Tools, and then double-click Computer Management.
4. In the left pane, click Disk Management.
5. In the lower-right pane, right-click the basic disk that you want to convert, and then click Convert to Dynamic Disk. 
   
   NOTE:You must right-click the gray area that contains the disk title on the left side of the Details pane. For example, right-click Disk 0.
6. Select the check box that is next to the disk that you want to convert (if it is not already selected), and then click OK.
7. Click Details if you want to view the list of volumes in the disk.
8. Click Convert.
9. Click Yes when you are prompted to convert, and then click OK.

How to Convert a Dynamic Disk to a Basic Disk

To change a dynamic disk back to a basic disk:

1. Back up all the data on all the volumes on the disk you want to convert to a basic disk.
2. Log on as Administrator or as a member of the Administrators group.
3. Click Start, and then click Control Panel.
4. Click Performance and Maintenance, click Administrative Tools, and then double-click Computer Management.
5. In the left pane, click Disk Management.
6. Right-click a volume on the dynamic disk that you want to change to a basic disk, and then click Delete Volume.
7. Click Yes when you are prompted to delete the volume.
8. Repeat steps 4 and 5 for each volume on the dynamic disk.
9. After you have deleted all the volumes on the dynamic disk, right-click the dynamic disk that you want to change to a basic disk, and then click Convert to Basic Disk. 
   
   NOTE:You must right-click the gray area that contains the disk title on the left side of the Details pane. For example, right-click Disk 1.