Users Guide

investigate the capacity of your peripheral devices to support a virtual disk that is larger than 1TB. For more information, see your
operating system and device documentation.
Number Of Physical Disks Per Virtual Disk
There are limitations on the number of physical disks that can be included in the virtual disk. These limitations depend on the
controller. When creating a virtual disk, the controllers support some stripes and spans (methods for combining the storage on
physical disks). Since, the number of total stripes and spans is limited, the number of physical disks that can be used is also limited.
The limitations on stripes and spans aect the possibilities for concatenation and RAID levels as follows:
• Maximum number of spans aects RAID 10, RAID 50, and RAID 60.
• Maximum number of stripes aects RAID 0, RAID 5, RAID 50, RAID 6, and RAID 60.
• Number of physical disks in a mirror is always 2. This property aects RAID 1 and RAID 10.
If RAID 50 and RAID 60, you can use a greater number of physical disks than is possible for other RAID levels. RAID 10 on a SAS
controller with rmware version 6.1 can use a maximum of 256 physical disks. However, the number of connectors on the controller
imposes limitations on how many physical disks can be included in a virtual disk when using RAID 10, RAID 50, or RAID 60. This is
because only a limited number of physical disks can be physically attached to the controller.
For information about the maximum number of physical disks supported by a virtual disk, see the virtual disk specications for the
controller in Supported Features.
Number Of Virtual Disks Per Controller
There are limitations on the number of virtual disks that can be created on the controller. For information about the maximum
number of virtual disks supported by a controller, see the virtual disk specications for the controller in Supported Features.
Calculation For Maximum Virtual Disk Size
The Create Virtual Disk Express Wizard displays the minimum and maximum values for the virtual disk size. This section describes
how the maximum possible size for the virtual disk is calculated based on the controller type. To identify the controller type, see RAID
Controller Technology: SATA and SAS.
SATA RAID Controllers
When using a SATA RAID controller, the controller calculates the maximum virtual disk size based on your RAID level selection and
the available physical disk space provided by all suitable physical disks attached to the controller. For example, if the controller
contains 12 physical disks with available space and you have specied a RAID 5, then the controller calculates the maximum virtual
disk size based on the disk space provided by the 12 physical disks, because the 12 physical disks can be included in a RAID 5.
SAS RAID Controllers
When using a SAS controller, the controller calculates the maximum virtual disk size based on the available disk space provided by
the minimum number of physical disks required to create the RAID level you selected. For example, if you specied a RAID 5, then
the controller calculates the maximum virtual disk size based on three physical disks, because only three physical disks are required to
create a RAID 5.
Channel-Redundant Virtual Disks
When creating a virtual disk, it is possible to use disks attached to dierent channels to implement channel redundancy. This
conguration might be used for disks that reside in enclosures subject to thermal shutdown.
NOTE: Channel redundancy only applies to controllers that have more than one channel and that attach to an external
disk enclosure.
Related links
Channel Redundancy
Creating A Channel-Redundant Virtual Disk
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