A striped volume with parity, which is also called RAID-5 in
Windows Server 2003, combines areas of free space from multiple hard disks
(from 3 to 32) into one logical volume.
Parity is redundant
information that is associated with a block of information. In products in
Windows Server 2003, parity is a calculated value that is used to reconstruct
data after a failure. RAID-5 volumes stripe data and parity across a set of
disks. When a disk fails, Windows Server 2003 uses the parity information to
re-create the data on the failed disk.
Because of this fault
tolerance, administrators favor using RAID-5 volumes when data integrity and
data input/output speed are both important. RAID-5 volumes cannot be mirrored,
and they cannot be extended. Any file system can be used on a RAID-5 volume,
including the FAT file system, the FAT32 file system, or the NTFS file system.
: Your operating system and boot files cannot reside on the RAID-5
disks. However, you can put the system swap file on a RAID-5
- A minimum of three hard disk drives. IDE, SCSI or mixed
architecture is permissible.
- All disks involved in the RAID-5 volume must be dynamic
- Operating system boot and system files must be on a
How to Set Up the Disk Management System
- Click Start, point to Administrative Tools, and then click Computer Management.
- Click the plus sign (+) next to Storage to open the Storage console tree.
- Click the Disk Management folder.
- On the View menu, point to Top, and then click Disk List. In the right pane, a column listing the attributes of each disk
in the system is displayed.
- On the View menu, point to Bottom, and then click Graphical View.
A color coded graphical view of the disks on the
system is displayed.
The Disk Description pane (that is displayed in gray) is on the
left side of the volume description that is displayed in color. The disk
description contains information about each disk's disk number, whether it is a
basic or dynamic configuration, its size, and its status (online or offline).
The volume descriptions are color-coded. They hold information on
each volume such as the drive letter (if assigned), whether it is allocated or
unallocated, the partition or volume size, and the health status of the volume.
How to Make Sure That Disks Are Set Up to Support RAID-5
- Disks: You must have a minimum of three disks to support
- Type: Any disks involved in striping must be dynamic. Conversion from
basic to dynamic goes very quickly without data loss. After you complete this
procedure, you must restart the computer.
- Capacity: The RAID-5 volume can take the whole disk or as little as 20
megabytes (MB) for each disk.
- Unallocated space: Any disks that you want to upgrade to a dynamic disk must
contain at least 1 MB of free space at the end of the disk for the upgrade to
succeed. Disk Management automatically reserves this free space when it creates
partitions or volumes on a disk, but disks with partitions or volumes that are
created by other operating systems might not have this free space available.
- Status: The status of all disks involved in a stripe volume must be
online when you create the striped volume.
- Device Type: You can install striping on any dynamic disk even if there are
mixed drive architectures on the computer. For example, IDE, EIDE, and SCSI
drives can all be used in one stripe volume.
How to Upgrade to Dynamic Disks
If the disks that are going to be involved in the stripe volume
are already dynamic disks, skip this section and go to the next section ("How
to Convert to Stripe Volume"). NOTE
: You must be logged on as an administrator or a member of the
Administrators group to complete this procedure. If your computer is connected
to a network, network policy settings may prevent you from completing this
To upgrade a basic disk to a dynamic disk:
- Before you upgrade disks, quit any programs that are
running on those disks.
- Right-click the gray Disk Description pane that is located to the left of the color-coded volume panes,
and then click Upgrade to Dynamic Disk.
- If the second disk in not a dynamic disk, follow the steps
earlier in this article to upgrade it to a dynamic disk.
How to Convert to RAID-5
In this scenario, there are four disks on the computer: Disk 0 ,
Disk 1, Disk 2 and Disk 3 . Disk 0 is reserved for the operating system and
boot files because they cannot reside on a RAID-5 volume. The other three disks
are the RAID-5 disks. There is 1 gigabyte (GB) of free unallocated space on
each disk to commit to the RAID-5 volume.NOTE
: 1 GB of free space on each of the three disks gives you a total
usable volume of 2 GB because of parity information that is written as part of
- In the Disk Management tool, right-click the unallocated
space on one of the dynamic disks where you want to create the RAID-5 volume,
and then click Create Volume.
- After the Create Volume Wizard starts, click Next.
- Click RAID-5 volume, and then click Next.
- Click the disks in the left pane under All Available Dynamic Disks, and then click the Add tab.
The disks that are displayed in the right pane
are labeled Selected.
- Look at the bottom of the Select Disk dialog box under the Size label.
The For All Selected Disks box displays the maximum size of the RAID-5 volume that you can
NOTE: The volume on each disk is the same size in the completed RAID-5
volume. For example, if you have 100 MB on the first disk, you have 100 MB on
the second disk. You can reduce the size of the volume from the maximum size
that the wizard automatically shows. To do so, click the arrow on the Disk Size box to lower the volume size on this disk. On a three-disk
system, the total RAID-5 volume storage size is double the size that you enter
here. The Total Volume Size box lists your total storage space.
- Click Next. At this time, you may want to assign a drive letter (you can
also do this at any other time). To do so, click Assign Drive Letter, and then enter an available drive letter.
Alternatively, you can click Do not assign drive letter or
path. You can also click Mount this volume on an empty folder
that supports drive paths. However, this selection is beyond the scope
of this article.
- Click Next.
- Click Format this partition with the following
settings, and then follow these steps:
- Type the file system type; FAT32 or NTFS is
- Leave the default selection in the Allocation Unit Size box.
- In the Volume Label box, you can keep the default "New Volume" label or you can type
your own label.
- At this time, you can click to select the Quick Format check box and the File and Folder Compression
check box. You can also defer both of these tasks if you like.
- Click Next, check your selection in the Summary window, and then click Finish.
The RAID-5 volume is displayed on the three disks on your
system. They have the same color code, the same drive letter (if you mapped the
drive during the procedure), and they are both the same size. If you clicked
the Quick Format
option, the status of the disks is displayed as "Regenerating"
while the drives are being formatted. After the disks are formatted, the status
of the disks is displayed as "Healthy". The RAID-5 volume is ready to be used;
you do not have to restart the computer.
- Never use a hardware-RAID solution and software RAID on the
- Operating system files and boot files cannot reside on the
- Microsoft recommends RAID-5 over mirrored volumes for
programs that require redundancy and are primarily read-oriented. Write
performance is reduced by the parity calculation. Also, a write operation
requires three times more memory than a read operation during typical
operation. This condition is caused by the parity calculation.
- RAID-5 volumes provide fault tolerance at a cost of one
additional disk for the volume. This means that if you use three 10-GB disks to
create a RAID-5 volume, the volume will have a 20-GB capacity. The remaining
10-GB are used for parity.
- RAID-5 volumes cannot be extended or mirrored.
Article ID: 323434 - Last Review: December 3, 2007 - Revision: 6.5
- Microsoft Windows Server 2003, Datacenter Edition (32-bit x86)
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