Many factors have made RAID 5 a very popular fault-tolerant design. RAID 5 can continue to function in the event of a single drive failure. If a hard disk were to fail in the array, the parity would re-create the missing data and continue to function with the remaining drives. The read performance of RAID 5 is improved over a single disk.
There are only a few drawbacks for the RAID 5 solution. These are as follows:
The costs of implementing RAID 5 are initially higher than other fault-tolerant measures requiring a minimum of three hard disks. Given the costs of hard disks today, this is a minor concern.
RAID 5 suffers from poor write performance because the parity has to be calculated and then written across several disks. The performance lag is minimal and won't have a noticeable difference on the network.
When a new disk is placed in a failed RAID 5 array, there is a regeneration time when the data is being rebuilt on the new drive. This process requires extensive resources from the server.
Figure 4 shows an example of RAID 5 striping with parity.Figure 9.4. RAID 5 striping with parity.