Software Support
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Virtual Disks
A virtual disk refers to a storage created by a RAID controller from one or more physical disks. Although a virtual disk
may be created from several physical disks, it is viewed by the operating system as a single disk. Depending on the RAID
level used, the virtual disk may retain redundant data if there is a disk failure or have particular performance attributes.
NOTE: Virtual disks can only be created on a RAID controller.
Related Links
Understanding RAID Concepts
Deleting A Virtual Disk
Considerations Before Creating Virtual Disks
Different controllers have particular characteristics in the way they implement virtual disks. These characteristics may
include use of disk space, limitations on the number of virtual disks per controller, and so on. It can be helpful to
understand these characteristics before creating virtual disks on the controller.
The following sections describe controller information that applies to virtual disks:
• Virtual Disk Considerations For Controllers
• Problems Associated With Using The Same Physical Disks For Both Redundant And Non-Redundant Virtual
Disks
• Virtual Disk Considerations On Systems Running Linux
• Number Of Physical Disks Per Virtual Disk
• Number Of Virtual Disks Per Controller
• Calculation For Maximum Virtual Disk Size
You may also want to review the following sections:
• RAID Controller Read, Write, Cache, And Disk Cache Policy
• Understanding Hot Spares
• Controller - Supported Stripe Sizes
• Rescanning To Update Storage Configuration Changes
• Time Delay In Displaying Configuration Changes
NOTE: In addition to this document, review the hardware documentation that is provided with the controllers.
Reviewing the hardware documentation along with this document may provide a better understanding of the
controller limitations.
Virtual Disk Considerations For Controllers
In addition to the considerations described in this section, you should also be aware of the controller limitations
described in Number of Physical Disks per Virtual Disk for the following controllers:
• PERC 5/E and PERC 5/I
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