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

8.4

RAID Types

3PAR InForm OS Concepts Guide InForm OS Version 2.3.1

8.4.1 RAID 0

On a RAID 0 logical disk, data is striped across rows of chunklets on different physical disks. The

number of chunklets in a RAID 0 set is known as the set size, which is always 1 for a RAID 0

logical disk. The number of sets in a row is known as the row size. The system accesses data

from a RAID 0 logical disk in step sizes, where the step size is the number of contiguous bytes

that the system accesses before moving on to the next chunklet. A RAID 0 logical disk improves

performance but provides no fault tolerance.

Figure 8-1 shows a RAID 0 logical disk with a set size of 1 and a row size of 3:

Figure 8-1. Data Striped Across Chunklets on a RAID 0 Logical Disk

8.4.2 RAID 1 and 10

On a RAID 10 logical disk, data is striped across RAID 1 (or mirrored) sets. A RAID 1 set is made

up of two or more chunklets that contain the same data. The chunklets in each set are

distributed across different physical disks, which may be located in different drive magazines

or even different drive cages. The number of chunklets in a RAID 1 set is the set size (or mirror

depth). The number of sets in each row is the row size. The maximum row size is 40. The system

accesses data from a RAID 10 logical disk in step sizes. A step size is the number of contiguous

bytes that the system accesses before moving on to the next chunklet. A RAID 1 set can

function with the loss of all but one of the chunklets in the set.

n-2

Step size

Set size

Row size

= C

hunklet

RAID 0 Logical Disk

n-1

...