3PAR InForm® OS 2.3.1 Concepts Guide (320-200112 Rev B, February 2010)

8.6
RAID Types
3PAR InForm OS Concepts Guide InForm OS Version 2.3.1
Figure 8-3 shows a RAID 50 logical disk with a set size of 3, and 2 sets in 1 row:
Figure 8-3. Data Striped Across RAID 5 Sets on a RAID 50 Logical Disk
8.4.4 RAID Multi-Parity
On a RAID Multi-Parity (MP) or RAID 6 logical disk, data is striped across rows of RAID MP sets.
A RAID MP set, or double parity set, must contain at least 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. RAID
MP set sizes of 8 and 16 chunklets are supported. The data and parity steps are striped across
each chunklet in the set. The chunklets in each RAID MP set are distributed across different
physical disks, which may be located in different drive magazines or even different drive cages.
The number of sets in a row is the row size. The system accesses the data from a RAID MP
logical disk in step sizes. The step size varies and is dependent on the size of the RAID MP set. A
RAID MP set can function with the loss of any two of the chunklets in the set.
A
p (E,F)
B
E
p (A,B)
F
C
p (G,H)
D
G
p (C,D)
H
Step size
Set size*
Row size
RAID 50 Logical Disk
= Chunklet
*Parity set
p (I,J) p (K,L)IJKL
p = Parity step