User`s guide

Striped volume

A volume that resides on two or more dynamic disks and whose data is evenly distributed across

equally-sized portions of disk space (called stripes) on those disks.

Access to data on striped volumes is usually faster than on other types of dynamic volumes, because

it can be performed simultaneously on multiple hard disks.

Unlike a mirrored volume (p. 90), a striped volume does not contain redundant information, so it is

not fault-tolerant.

A striped volume is also known as a RAID-0 volume.

Mirrored volume

A fault-tolerant volume whose data is duplicated on two physical disks (p. 90).

Each of the two parts of a mirrored volume is called a mirror.

All of the data on one disk is copied to another disk to provide data redundancy. If one of the hard

disks fails, the data can still be accessed from the remaining hard disks.

Volumes that can be mirrored include the system volume (p. 93) and a boot volume (p. 83).

A mirrored volume is sometimes called a RAID-1 volume.

Note: No redundancy provided by the dynamic volumes architecture can replace the proper backup procedure.

If you want to be sure of the safety of your data, the best policy is to combine both precautions.

RAID-5 volume

A fault-tolerant volume (p. 93) whose data is striped in equally-sized blocks across an array of three

or more disks (p. 84).

Fault tolerance is achieved by using parity, a calculated value that can be used to reconstruct data in

case of a failure. Parity is also striped across the disk array. Parity is always stored on a different disk

than the data itself. If one of the hard disks fails, the portion of the RAID-5 volume that was on that

hard disk can be recreated from the remaining data and the parity.

A RAID-5 volume has a higher volume-size-to-disk-space ratio than a mirrored volume. For example,

suppose that you want to use 120 GB of disk space to create a fault-tolerant volume:

 By using two 60-GB disks, you can create a 60-GB mirrored volume.

 By using three 40-GB disks, you can create an 80-GB RAID-5 volume.

4.4 Active, system, and boot volumes

Some volumes on the disks of your machine contain information that is necessary for the machine to

start and for a particular operating system to run. Each such volume is called active, system, or boot,

depending on its function.

If only one Windows operating system is installed on your machine, a single volume is often the

active, system, and boot volume at the same time.

Because of their special role, you should use extra caution when performing operations with these

volumes. Some operations with these volumes have limitations as compared to ordinary volumes.