You can scale a Hadoop cluster by adding new servers or whole server racks to the cluster, and by increasing memory in the master nodes. Use the following guidelines to scale your existing Hadoop cluster:
Ensure there is potential free space in the data center near the Hadoop cluster. This space should be able to accommodate the power budget for more racks.
Plan your network so that you can add servers over time.
It might be possible to add more disks and RAM to the existing servers, and extra CPUs if the servers have spare sockets, expanding an existing cluster without adding more racks or modifying the network.
When performing a hardware upgrade in a live cluster, plan your expansion carefully beforehand. The process can take considerable time and effort.
As your cluster grows, consider adding more memory to the master servers.
