Scalability is a system’s ability to remain responsive as workload increases. Responsiveness means keeping the error rate below an acceptable error budget for a defined service-level objective. section 1.4.2 section 1.4.3
Scalability is not a property of one component alone. It emerges from multiple concurrent components and their interactions, because a single component cannot handle unbounded load. section 1.0 section 1.4.3
A practical test
A web application may work correctly with modest demand yet fail its service objective as requests increase. Adding components can support scale, but the resulting guarantee depends on how those components interact. section 1.0 section 1.4.3


























