Advantages

The advantage of clustering servers for HA is seen if one node in the cluster fails, another node can resume the task of the failed node, and users experience no interruption of access.

The advantages of clustering servers for scalability include increased application performance and a greater number of users that can be supported. You can imagine a cluster of servers as a single computing resource. With the total redundancy of multiple servers that will make the system work if other servers fail, the cluster can help achieve greater system uptime (i.e.: periods of time when your system is available).

Clustering can be implemented at different levels,

• Hardware
• Operating systems
• Systems management and applications.
• Middleware

The more layers, the more reliable, scalable and manageable the cluster is.