You can vertically and horizontally scale the Sitecore Experience Platform to meet your requirements. Choose a default topology as a starting point or design your own.
You can vertically scale the Sitecore Experience Platform by:
Adding more resources (RAM, CPU) to a server or web application in your topology.
Combining or splitting web application roles.
A single web application can be configured to perform multiple roles. The following diagram shows a subset of roles in an XP topology where Content Management, xDB Reporting, and xDB Processing run as a single combined application:
In an on-premise or IaaS setting, combined roles run as a single application with one web root and one application pool in IIS. In Azure, combined roles run as a single web app.
In a fully vertically scaled environment, each role runs as a standalone application:
You can split or combine roles to suit your scaling needs. For more information about supported combinations, refer to the scaling section of each role's configuration page. For example: Content Delivery, xConnect Collection.
You can horizontally scale the Sitecore Experience Platform by dedicating multiple web applications to the same role within a topology. For example, you can deploy two instances of the Content Delivery role behind a load balancer:
Some roles, such as the xConnect Search Indexer, do not support horizontal scaling.