HP 3PAR InForm OS 3.1.1 Concepts Guide

Figure 6 Data Striped Across RAID MP Sets on a RAID MP Logical Disk
Logical Disk Size and RAID Types
A logical disk is a collection of physical disk chunklets arranged as rows of RAID sets. On F-Class
and T-Class systems all chunklets are 256 MB. On P10000 systems all chunklets are 1 GB. All
systems round up so that the logical disk size is divisible by the size of one chunklet, either 1 GB
or 256 KB. The total size of the logical disk is determined by the number of data chunklets in the
RAID set.
• A RAID 0 or RAID 1 logical disk must contain at least one chunklet.
• A RAID 5 set, or parity set, must contain at least three chunklets. A RAID 5 set with three
chunklets has a total of two chunklets of space for data and one chunklet of space for parity.
The system default is four chunklets: three for data and one for parity (3+1).
• A RAID MP set, or double-parity set, must contain at least 8 chunklets. RAID MP set sizes of
8 and 16 chunklets are supported. The system default is 8 chunklets. A RAID MP set with 8
chunklets has a total of 6 chunklets of space for data and 2 chunklets of space for parity (6+2).
NOTE: The system also rounds up the size of virtual volumes, CPGs, and CPG growth increments
to be divisible by the size of one chunklet, either 1 GB or 256 KB.
Logical Disk Size and RAID Types 39