# Scalability

> The degree to which a system keeps its throughput and latency as load grows, by adding resources.

Record: `architecture:scalability`
Kind: quality-attribute
Layer: [Performance Core](https://banes-lab.com/records/layer/performance-core.md)
Severity: contextual
Scope: service, system, infrastructure
Canonical: https://banes-lab.com/ontology#architecture-scalability

Listed in [Architecture principles](https://banes-lab.com/api/records/architecture.md), after [Flyweight Pattern](https://banes-lab.com/records/architecture/flyweight-pattern.md) and before [Horizontal Scaling](https://banes-lab.com/records/architecture/horizontal-scaling.md).

## Repair

- Refactored by: Add Caching, [Partitioning](https://banes-lab.com/records/architecture/partitioning.md), Async Processing, Scaling
- Detected by: saturation under load test
- Violated by: single bottleneck preventing growth
- Measured by: throughput under increasing load
- Enforced by: load tests, SLO gates

## Requires

- [Load Model](https://banes-lab.com/records/lexicon/load-model.md)
- [Bottleneck Awareness](https://banes-lab.com/records/lexicon/bottleneck-awareness.md)

## Reinforces

- [Performance Engineering](https://banes-lab.com/records/architecture/performance-engineering.md)

## Enables

- [Growth Handling](https://banes-lab.com/records/lexicon/growth-handling.md)

## Conflicts with

- [Fixed-Capacity Design](https://banes-lab.com/records/lexicon/fixed-capacity-design.md)

## In tension with

- [Simplicity](https://banes-lab.com/records/lexicon/simplicity.md)
- [Consistency](https://banes-lab.com/records/architecture/consistency.md)

## Tensions

- [Scalability / Simplicity](https://banes-lab.com/records/tension/scalability-simplicity.md)
- [Scalability / Consistency](https://banes-lab.com/records/tension/consistency-scalability.md)

## Severity

- [contextual](https://banes-lab.com/records/vocabulary/severity-contextual.md)

## Category

- [Scalability / Performance / Optimization](https://banes-lab.com/records/architecture-category/scalability-performance-optimization.md)

## Reinforced by

- [Service Discovery](https://banes-lab.com/records/architecture/service-discovery.md)
- [Message Broker](https://banes-lab.com/records/architecture/message-broker.md)
- [CQRS](https://banes-lab.com/records/architecture/command-query-responsibility-segregation.md)
- [Eventual Consistency](https://banes-lab.com/records/architecture/eventual-consistency.md)
- [Elasticity](https://banes-lab.com/records/architecture/elasticity.md)
- [Load Balancing](https://banes-lab.com/records/architecture/load-balancing.md)
- [Partitioning](https://banes-lab.com/records/architecture/partitioning.md)
- [Caching](https://banes-lab.com/records/architecture/caching.md)
- [Throughput](https://banes-lab.com/records/architecture/throughput.md)
- [Algorithmic Efficiency](https://banes-lab.com/records/architecture/algorithmic-efficiency.md)
- [Memory Efficiency](https://banes-lab.com/records/architecture/memory-efficiency.md)
- [Stateless Processing](https://banes-lab.com/records/architecture/stateless-processing.md)
- [Replication](https://banes-lab.com/records/architecture/replication.md)
- [Microservices](https://banes-lab.com/records/architecture/microservices.md)

## Linked from

- [Above one tier, reduction](https://banes-lab.com/software-architecture/scale/above-one-tier-reduction.md)
- [Scale follows determinism](https://banes-lab.com/software-architecture/scale/scale-follows-determinism.md)
- [Runtime Discovery / Dynamic Binding](https://banes-lab.com/ontology/principles/architecture-category-runtime-discovery-dynamic-binding.md)
- [Event / Messaging / Asynchronous Architecture](https://banes-lab.com/ontology/principles/architecture-category-event-messaging-asynchronous-architecture.md)
- [Scalability / Performance / Optimization](https://banes-lab.com/ontology/principles/architecture-category-scalability-performance-optimization.md)
- [Streaming / Pipeline / Dataflow Processing](https://banes-lab.com/ontology/principles/architecture-category-streaming-pipeline-dataflow-processing.md)
- [Self-Healing / Recovery / Deployment Safety](https://banes-lab.com/ontology/principles/architecture-category-self-healing-recovery-deployment-safety.md)
- [Codebase / System Architecture Styles](https://banes-lab.com/ontology/principles/architecture-category-codebase-system-architecture-styles.md)
- [Transactions / State / Concurrency](https://banes-lab.com/ontology/principles/architecture-category-transactions-state-concurrency.md)
- [Quality Attributes](https://banes-lab.com/ontology/lexicon/lexicon-category-quality-attributes.md)
- [Scalability / Performance / Optimization](https://banes-lab.com/ontology/lexicon/lexicon-category-scalability-performance-optimization.md)
- [Severity levels](https://banes-lab.com/ontology/schema/the-vocabulary-severity.md)
- [The resolutions](https://banes-lab.com/ontology/schema/the-resolutions.md)