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Chapter 2. Introducing the 3ware® 9590SE-4ME RAID Controller

10

Determining What RAID Level to Use

Your choice of which type of RAID unit (array) to create will depend on your 
needs. You may wish to maximize speed of access, total amount of storage, or 
redundant protection of data. Each type of RAID unit offers a different blend 
of these characteristics.

The following table provides a brief summary of RAID type characteristics. 

                                      

You can create one or more units, depending on the number of drives you 
have installed.

To make the most efficient use of drive capacity, it is advisable to use drives 
of the same capacity. This is because the capacity of each drive is limited to 
the capacity of the smallest drive in the unit. 

The total array capacity is defined as follows:

                                      

RAID 0

Provides performance, but no fault tolerance.

RAID 1

Provides fault tolerance and a read speed advantage over non-
RAID disks.

RAID 5

This type of unit provides performance, fault tolerance, and high 
storage efficiency.

RAID 10

A combination of striped and mirrored units for fault tolerance 
and high performance.

Single Disk

Not a RAID type, but supported as a configuration. 

Provides for maximum disk capacity with no redundancy.

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 10

(number of drives / 2) X (capacity of smallest drive)