Avago Technologies 3ware SAS 9750-4i - Manual (Page 24)

Chapter 1. Introduction to the 3ware Command Line Interface
16 3ware SATA+SAS RAID Controller Card CLI Guide, Version 10.0
Using Drive Capacity Efficiently
To make the most efficient use of drive capacity, it is advisable to use drives
of the same capacity in a unit. This is because the capacity of each drive is
limited to the capacity of the smallest drive in the unit.
The total unit capacity is defined as follows:
3 RAID 0
RAID 1 with hot spare
RAID 5
4 RAID 5 with hot spare
RAID 10
Combination of RAID 0, RAID 1, single disk
5 RAID 6
RAID 5 with hot spare
RAID 10 with hot spare
Combination of RAID 0, RAID 1, hot spare, single disk
6 or more RAID 6
RAID 6 with hot spare
RAID 50
Combination of RAID 0, 1, 5, 6,10, hot spare, single disk
Table 3: Possible Configurations Based on Number of Drives
# Drives Possible RAID Configurations
Table 4: Drive Capacity
RAID Level Capacity
Single Disk Capacity of the drive
RAID 0 (number of drives) X (capacity of the smallest drive)
RAID 1 Capacity of the smallest drive
RAID 5 (number of drives - 1) X (capacity of the smallest drive)
Storage efficiency increases with the number of disks:
storage efficiency = (number of drives -1)/(number of drives)
RAID 6 (number of drives - 2) x (capacity of the smallest drive)
RAID 10 (number of drives / 2) X (capacity of smallest drive)
RAID 50 (number of drives - number of groups of drives) X (capacity of the
smallest drive)