Elasticity refers to dynamic online expansion of the deployed cluster. One can add more storage nodes to increase the capacity, performance, reliability, or all of the above. Let’s take a look at how growing business can benefit from on-demand cluster expansion feature in Oracle NoSQL Database:
Increase Data Capacity:
As need to acquire data increases, you can increase the data capacity of your database by either adding more disk drives to the existing storage nodes and changing the capacity parameter on each Storage Node (SN) or adding more storage nodes with its own compute power and local disk drives.
Once you are done adding more resources to your cluster, you can clone a new topology which takes into account newly added capacity of the cluster and based on that it automatically adds more shards and/or create new Replication Nodes (RN). If Replication Factor (RF) is kept same then more shards gets added to the cluster providing more data capacity.
Figure 1: Showing storage expansion by adding more shards leading to increased storage capacity and higher performance.
Increase Throughput :
Sometimes it is the growing web traffic on your business application that demands more I/O capacity and throughput (operations/sec) performance.
Though performance of a cluster is a complex equation of many variables (like speed of your disk drives, number of disk drives, CPU speed, network bandwidth etc) but it can also be expressed in terms of number of shards and the replication factor of the cluster. The more the shards your cluster has the better read and write throughput and higher replication factor means more places to service the read operation, which converts very well into higher read performance.
Increase Replication Factor:
Availability is an important aspect of scalable NoSQL database. In Oracle NoSQL Database not only you can increase the replication factor (RF) of each shard in the same datacenter but can also add a new datacenter with its own replication factor. For example you can keep the majority of replication nodes in the primary datacenter e.g. RF=3 and for geographical availability you can add new datacenter with RF=1.
Figure 2: Showing increased availability by increasing the replication factor (RF) where the new storage nodes are in another geographic location.
So any of the above factors can trigger the cluster expansion needs and Oracle NoSQL Database makes the process very simple yet maintaining the SLAs of the cluster.