Features

RAID 0

RAID 1

RAID 1E

RAID 5

RAID 5EE

Minimum # Drives

2

2

3

3

4

Data Protection

No Protection

Single-drive failure

Single-drive failure

Single-drive failure

Single-drive failure

Read Performance

High

High

High

High

High

Write Performance

High

Medium

Medium

Low

Low

Read Performance (degraded)

N/A

Medium

High

Low

Low

Write Performance (degraded)

N/A

High

High

Low

Low

Capacity Utilization

100%

50%

50%

67% – 94%

50% – 88%

Typical ApplicationsHigh End Workstations, data logging, real-time rendering, very transitory dataOperating System, transaction databasesOperating system, transaction databasesData warehousing, web serving, archivingData warehousing, web serving, archiving
  Features

RAID 6

RAID 10

RAID 50

RAID 60

Minimum # Drives

4

4

6

8

Data Protection

Two-drive failure

Up to one disk failure in each sub-array

Up to one disk failure in each sub-array

Up to two disk failure in each sub-array

Read Performance

High

High

High

High

Write Performance

Low

Medium

Medium

Medium

Read Performance (degraded)

Low

High

Medium

Medium

Write Performance (degraded)

Low

High

Medium

Low

Capacity Utilization

50% – 88%

50%

67% – 94%

50% – 88%

Typical ApplicationsData archive, backup to disk, high availability solutions, servers with large capacity requirementsFast databases, application serversLarge databases, file servers, application serversData archive, backup to disk, high availability solutions, servers with large capacity requirements

 

Types of RAID Arrays

  Types of RAIDSoftware-BasedHardware-BasedExternal Hardware
DescriptionBest used for large block applications such as data warehousing or video streaming. Also where servers have the available CPU cycles to manage the I/O intensive operations certain RAID levels require.

Included in the OS, such as Windows®, Netware, and Linux. All RAID functions are handled by the host CPU which can severely tax its ability to perform other computations.

Best used for small block applications such as transaction oriented databases and web servers.

Processor-intensive RAID operations are off-loaded from the host CPU to enhance performance.

Battery-back write back cache can dramatically increase performance without adding risk of data loss.

Connects to the server via a standard controller. RAID functions are performed on a microprocessor located on the external RAID controller independent of the host.
AdvantagesLow price

Only requires a standard controller

Data protection and performance benefits of RAID

More robust fault-tolerant features and increased performance versus software-based RAID

OS independent

Build high-capacity storage systems for highend servers