## Understanding RAID level-5

RAID level-5 requires a minimum of three physical drives. This RAID level stripes data and parity across all drives in the array. When you assign RAID level-5 to an array, the capacity of the array is reduced by the capacity of one drive (for data-parity storage).

RAID level-5 offers both data protection and increased throughput. RAID level-5 gives you higher capacity than RAID level-1, but RAID level-1 offers better performance.

RAID level-5 requires a minimum of 3 drives and, depending upon the level of firmware and the stripe-unit size, supports a maximum of 8 or 16 drives.

The following illustration is an example of a RAID level-5 logical drive.

### RAID level-5 example

Start with four physical drives. |
Create an array using three of the physical drives, leaving the fourth as a hot-spare drive. |
Then, create a logical drive within that array. |
The data is striped across the drives, creating blocks. Notice that the storage of the data parity (denoted by *) also is striped, and it shifts from drive to drive. A parity block (*) contains a representation of the data from the other blocks in the same stripe. For example, the parity block in the first stripe contains data representation of blocks 1 and 2. |
If a physical drive fails in the array, the ServeRAID controller switches read and write requests to the remaining functional drive in the RAID level-5 array, which is a hot-spare drive. |

See also

Understanding RAID technology
Understanding stripe-unit size
Selecting a RAID level
RAID level-0
RAID level-1
RAID level-1 Enhanced
RAID level-5 Enhanced
RAID level-x0