Dynamic disk introduction - Characteristics of Dynamic disk

A Dynamic disk is a physical disk with features that basic disks do not have, such as support for volumes spanning multiple disks. Dynamic disks use a hidden database to track information about dynamic volumes on the disk and other dynamic disks in the computer. Dynamic disk management is a data/hard disk management method on the Microsoft Windows platform, first introduced with Windows 2000 operating system. The basic concept was put to use on Unix platform years earlier. There are five types of Dynamic volumes: Simple Volume, Striped Volume, Spanned Volume, Mirrored Volume, RAID 5 Volume.

What’s the difference between Basic and Dynamic Disks in Windows XP/2000/2003/Vista?

Microsoft Windows XP, Windows 2000, Windows Server 2003, and Windows Vista offer two types of disk storage: basic and dynamic.

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, Windows Server 2003 and Windows XP. A disk that has been initialized for basic storage is called a basic disk. A basic disk contains basic volumes, such as primary partitions, extended partitions, and logical drives. Additionally, basic volumes include multi-disk volumes that are created by using Windows NT 4.0 or earliereditions, 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 the Windows XP Professional, Windows 2000 and Windows Server 2003. A disk that has been 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. With dynamic storage, you can perform disk and volume management without restarting the Windows.

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 the 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, or the Standard, Enterprise and the Data Center versions of Windows Server 2003 or the Starter, Basic, Home Premium, Business, Enterprise and Ultimate of Windows Vista .

Storage types are separated 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.

Dynamic Storage Terms

A volume is a storage unit made from free space on one or more disks. It can be formatted with a file system and assigned a drive letter. Volumes on dynamic disks have the following types: simple, spanned, mirrored, striped, or RAID-5.

A simple volume uses free space from a single disk. It can be a single region on a disk or consist of multiple, concatenated regions. A simple volume can be extended within the same disk or onto additional disks. If a simple volume is extended across multiple disks, it becomes a spanned volume.

A spanned volume is created from free disk space that is linked together from multiple disks. You can extend a spanned volume onto a maximum of 32 disks. A spanned volume cannot be mirrored and is not fault-tolerant.

A striped volume is a volume whose data is interleaved across two or more physical disks. The data on this type of volume is allocated alternately and evenly to each of the physical disks. A striped volume cannot be mirrored or extended and is not fault-tolerant. Striping is also known as RAID-0.

A mirrored volume is a fault-tolerant volume whose data is duplicated on two physical disks. All of the data on one volume is copied to other disks for storage. If one of the disks fails, the data can still be accessed from the remaining disk. A mirrored volume cannot be extended. Mirroring is also known as RAID-1.

A RAID-5 volume is a fault-tolerant volume whose data is striped across an array of three or more disks. Parity (a calculated value that can be used to reconstruct data after a failure) is also striped across the disk array. If a physical disk fails, the portion of the RAID-5 volume that was on that failed disk can be re-created from the remaining data and the parity. A RAID-5 volume cannot be mirrored or extended.

The system volume contains the hardware-specific files needed to load the Windows (for example, Ntldr, Boot.ini, and Ntdetect.com). The system volume can be, but does not have to be, the same as the boot volume.

The boot volume contains the Windows operating system files located in the %Systemroot% and %Systemroot%\System32 folders. The boot volume can be, but does not have to be, the same as the system volume.

Compared to basic disk, dynamic disk has following characteristic:

(1) It may change disk capacity at random. You can change the capacity of disk without losing data and restarting computer. That of basic disk may lose data.

(2) Disk space limitation. Dynamic disk may be extended to discontinuous disk space in disk. It also may create volume collection that crosses disks and gather several disks into a big volume collection. While basic disk partition must be in a continual space on the same disk which cannot cross disks. The partition maximum capacity is disk capacity.

(3) Volume collection or partition number. Dynamic disk does not have limit about the volume collection number on a disk. But basic disk only can divide into 4 or 3 primary partitions and 1 extended partition mostly in a disk. But extended partition may contain several logical drives.
Disk allocation information. Disk allocation information of dynamic disk is stored in disk, not in registry or other place that is not good for renew. At the same time disk allocate information can be copied to other dynamic disks. Thus, it is convenient for dynamic disk to be transplanted between different machines.

Visiting Speed of disk. Basic read-write speed is determined by hardware, which cannot promote disk efficiency without extra extend. But dynamic disk may create striped volume to deal with read-write operations to many disks at the same time, thus promoting disk efficiency.

Fault-tolerant function of disk. The basic disk has no fault-tolerance, nor provides data protection measures. If the disk is out of order without backup, data will be lost. While dynamic disk may create the mirror volume, data would be “mirrored” automatically to mirror volume. thus reducing data loss to the lowest. At the same time, parity check provided by Raid-5 also can protect data from losing.

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