Users Guide

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 6/E and PERC 6/I
• PERC H310 Adapter, PERC H310 Mini Monolithic, and PERC H310 Mini Blades
• PERC H700, PERC H710 Adapter, PERC H710 Mini Blades, PERC H710 Mini Monolithic
• PERC H800, PERC H810 Adapter
• PERC H330 Adapter, PERC H330 Mini Monolithic, PERC H330 Mini Blades, PERC H330 Embedded
• PERC H730P Adapter, PERC H730P Mini Monolithic, PERC H730P Mini Blades, PERC H730P Slim
• PERC H730 Adapter, PERC H730 Mini Monolithic, PERC H730 Mini Blades
• PERC H830 Adapter
• PERC FD33xD/FD33xS
NOTE: The order of the controllers displayed on Storage Management may differ with the order of
the controllers displayed in the Human Interface (HII) and PERC Option ROM. The order of the
controllers does not cause any limitation.
The following considerations apply when creating virtual disks:
• Creating virtual disks on controllers — When you create a virtual disk, you specify which physical disks
are to be included in the virtual disk. The virtual disk you create spans the specified physical disks.
Depending on the size of the virtual disk, the virtual disk may not consume all of the space on the
physical disks. Any leftover space on the physical disks cannot be used for a second virtual disk unless
the physical disks are of equal size. In addition, when the physical disks are of equal size and you use
the leftover space for a second virtual disk, this new virtual disk cannot expand to include any physical
disks not included in the original virtual disk.
• Space allocation when deleting and creating virtual disks on controllers — When you delete a virtual
disk, you free up or make available space on the physical disks that was being used by the deleted
virtual disk. If you have created several virtual disks on a disk group, then deleting virtual disks can
result in pockets of free space residing in various locations on the physical disks. When you create a
new virtual disk, the controller 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.
• 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 indicating 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.
• 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.
• 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.
• Virtual disk names not stored on controller — The names of the virtual disks that you create are not
stored on the controller. If you reboot using a different operating system, the new operating system
may rename the virtual disk using its own naming conventions.
• 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.
141