Vertical scaling changes the size or type of one virtual machine or database server. Scaling up adds computing resources; scaling down removes them. It is the cloud equivalent of giving one hard-working machine a bigger backpack. section 3.5.1 section 10.7
Use vertical scaling when demand changes but one larger or smaller resource remains the simplest fit:
- Start with a small VM and change its size when the application needs more or fewer resources. section 3.5.1
- Increase an Azure SQL database's compute size or memory during traffic spikes, then choose a smaller configuration when demand falls. section 10.4.4
- Choose horizontal scaling instead when distributing workload across multiple VMs or database replicas is more appropriate. section 3.5.1 section 10.4.4
Banning Books prepares for peak traffic
During Banned Books Week or Ultra Black Friday, Banning Books can scale its Azure SQL database from a Standard tier with 100 DTUs to a higher-performance tier. The larger configuration helps process heavier reads and writes from orders and browsing. Azure CLI can apply the change with `az sql db update --name BanningBooksDB --resource-group BanningRG --server BanningBooksServer --service-objective S3`. section 10.4.4
