HP 3PAR StoreServ Concepts Guide: HP 3PAR OS 3.1.3

Physical Disks
A physical disk is a hard drive mounted on a drive magazine located in an HP 3PAR storage
system drive cage. For more information about physical disks and the HP 3PAR storage system
hardware platforms, see “HP 3PAR Storage System Hardware” (page 64).
Chunklets
Physical disks are divided into chunklets. Each chunklet occupies contiguous space on a physical
disk. On F-Class and T-Class systems, all chunklets are 256 MB. On 10000 and 7000 systems,
all chunklets are 1 GB. Chunklets are automatically created by the HP 3PAR Operating System
(HP 3PAR OS), and they are used to create LDs. A chunklet is assigned to only one LD. For more
information about chunklets, see “Chunklets” (page 34).
LDs
A LD is a collection of physical disk chunklets arranged as rows of RAID sets. Each RAID set is
made up of chunklets from different physical disks. LDs are pooled together in CPGs, which allocate
space to virtual volumes. The underlying LDs are automatically created by the HP 3PAR OS when
you create CPGs. The RAID type, space allocation, growth increments, and other LD parameters
can be set when you create a CPG or modified later. HP 3PAR storage systems support the following
RAID types:
• RAID 0
• RAID 10 (RAID 1)
• RAID 50 (RAID 5)
• RAID MP (Multi-Parity) or RAID 6
For a detailed discussion of LDs and RAID types, see “LDs” (page 36).
Common Provisioning Groups
A CPG is a virtual pool of LDs that allocates space to virtual volumes on demand. A CPG allows
virtual volumes to share the CPG resources. You can create fully provisioned virtual volumes (FPVVs)
and thinly-provisioned virtual volumes (TPVVs) that draw space from a CPG LD pool. For more
information about CPGs, see “Common Provisioning Groups” (page 41).
Virtual Volumes
Virtual volumes draw their resources from CPGs, and volumes are exported as logical unit numbers
(LUNs) to hosts. Virtual volumes are the only data layers visible to the hosts. You can create physical
copies of virtual volumes that remain available if the original base volume becomes unavailable.
Before creating virtual volumes, you must first create CPGs to allocate space to the virtual volumes.
For more information about virtual volumes, see “Virtual Volumes” (page 44).
Fully-provisioned Virtual Volumes
An FPVV is a volume that uses LDs that belong to a CPG. Unlike TPVVs, FPVVs have a set amount
of user space that is allocated for user data. The FPVV size is fixed, and the size limit is 16 TB.
For more information about fully provisioned virtual volumes, see “Fully-Provisioned Virtual
Volumes” (page 45).
8 Overview