Scaling for high availability

Horizontal scaling

Involves adding or removing resources to handle changes in workload demand. It is commonly used in public cloud in workload demand. It is commonly used in public cloud infrastructure and is designed to enhance availability

Horizontal scaling example

In a two-tier architecture with a load balancer and a fleet of VMs serving as application servers, as metrics (such as KPIs) indicating increased activity cross a threshold, you can scale out by adding more individual VMs to handle the application load. When reducing resources due to decreased demand, called scaling in

Vertical Scaling

Vertical scaling is typically performed within a single or VM by adding resources like memory, CPU, disk space, or network throughput. It’s often suitable for private clouds or on-premises data centers

Vertical scaling considerations

May involve an interruption of service, as you may need to power off the VM or shut down the hardware to make resource upgrades