3PAR InForm® OS 2.2.4 CLI Administrator's Manual (320-200113 Rev A, March 2009)

7.3
Overview
InForm OS Version 2.2.4 3PAR InForm OS CLI Administrator’s Manual
7.1 Overview
Virtual volumes are built on logical disks, which are built on physical disks, and are the only
logical storage component visible to hosts.
7.2 System Guidelines for Volume Creation
When opting to specify advanced parameters for logical disk creation, use the following
guidelines to ensure maximum performance and optimal reliability in the volumes supported
by those logical disks:
 Chunklets in the same RAID set should be from different drive magazines or drive cages.
 Chunklets in the same row should be from different physical disks. In other words, a
physical disk should not appear twice in the same row.
 Chunklets should belong to a disk that is connected through the primary path to the logical
disk’s owner node.
 The system should use as many physical disks as possible.
 The load on all physical disks should be balanced.
 The system should use the largest possible row size.
7.3 Creating Logical Disks and Virtual Volumes
When creating base virtual volumes, the system automatically creates the logical disks on
which the virtual volumes are built. You can either create stand-alone virtual volumes or virtual
volumes which draw their logical disks from CPGs. See 7.10 Common Provisioning Groups on
page 7.10 for information about creating and allocating storage using CPGs. For additional
information about base volumes and other types of volumes, refer to the InForm OS Concepts
Guide.
NOTE: When creating a volume, the underlying logical disks are rounded up to
the next nearest 256 MB. For more information about logical disk size, see the
InForm OS Concepts Guide.