Logical Disk Size And Raid Types - HP 3PAR StoreServ 7200 2-node Manual

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 StoreServ 10000 and StoreServ 7000 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 (RAID 6), 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). On StoreServ 10000 and StoreServ 7000 systems, RAID 6 set sizes of (4+2),
(6+2), (8+2), (10+2), and (14+2) are supported.
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.
38 Logical Disks