User's Manual

Virtual Disks 199
must decide which free space on the physical disks to allocate to the new
virtual disk. The PERC controllers look for the largest area of free space
and allocate this space to the new virtual disk.
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SCSI limitation of 2TB —Virtual disks created on a PERC controller
cannot be created from physical disks with an aggregate size greater than
2TB. This is a limitation of the controller implementation. For example,
you cannot select more than 30 physical disks that are 73GB in size,
regardless of the size of the resulting virtual disk. When attempting to
select more than 30 disks of this size, a pop-up message is displayed that
indicates that the 2TB limit has been reached, and that you should select a
smaller number of physical disks. The 2TB limit is an industry-wide SCSI
limitation.
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Expanding virtual disks —You can only use the Reconfigure task to
expand a virtual disk that uses the full capacity of its member physical
disks. For more information, see Virtual Disk Task: Reconfigure (Step 1 of
3).
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Reconfiguring virtual disks —The Reconfigure task is not available when
you have more than one virtual disk using the same set of physical disks.
You can, however, reconfigure a virtual disk that is the only virtual disk
residing on a set of physical disks. For more information, see Virtual Disk
Task: Reconfigure (Step 1 of 3).
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Virtual disk names not stored on controller —The names of the virtual
disks that you create are not stored on the controller. This means that if
you reboot using a different operating system, the new operating system
may rename the virtual disk using its own naming conventions.
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Creating and deleting virtual disks on cluster-enabled controllers —
There are particular considerations for creating or deleting a virtual disk
from a cluster-enabled controller.
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Implementing channel redundancy —A virtual disk is channel-redundant
when it maintains redundant data on more than one channel. If one of the
channels fails, data is not lost because redundant data resides on another
channel. For more information, see Channel Redundancy and Thermal
Shutdown.