# RAID Redundancy

> A technique for spreading data across several disks with mirroring or parity, so the loss of a disk loses no data.

Record: `architecture:raid-redundancy`
Kind: technique
Layer: [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md)
Severity: contextual
Scope: storage, redundancy, infrastructure
Aliases: Redundant Array of Independent Disks
Canonical: https://banes-lab.com/ontology#architecture-raid-redundancy

Listed in [Architecture principles](https://banes-lab.com/api/records/architecture.md), after [Graceful Shutdown](https://banes-lab.com/records/architecture/graceful-shutdown.md) and before [Schema Validation](https://banes-lab.com/records/architecture/schema-validation.md).

## Repair

- Refactored by: Place data on a mirrored or parity RAID array (RAID 1/5/10)
- Detected by: total data loss when one drive fails
- Violated by: durable data written to a single disk with no physical redundancy
- Measured by: tolerated simultaneous disk failures
- Enforced by: storage architecture review

## Requires

- [Multiple Physical Disks](https://banes-lab.com/records/lexicon/multiple-physical-disks.md)

## Reinforces

- [Redundancy](https://banes-lab.com/records/architecture/redundancy.md)
- [Fault Tolerance](https://banes-lab.com/records/architecture/fault-tolerance.md)

## Enables

- [Disk-Failure Survival](https://banes-lab.com/records/lexicon/disk-failure-survival.md)
- [Parity-Based Recovery](https://banes-lab.com/records/lexicon/parity-based-recovery.md)

## Conflicts with

- [Single-Disk Point of Failure](https://banes-lab.com/records/lexicon/single-disk-point-of-failure.md)

## In tension with

- [Write Amplification](https://banes-lab.com/records/lexicon/write-amplification.md)

## Tensions

- [RAID Redundancy / Write Amplification](https://banes-lab.com/records/tension/raid-redundancy-write-amplification.md)

## Severity

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

## Category

- [Self-Healing / Recovery / Deployment Safety](https://banes-lab.com/records/architecture-category/self-healing-recovery-deployment-safety.md)

## Linked from

- [Error Handling / Resilience](https://banes-lab.com/ontology/principles/architecture-category-error-handling-resilience.md)
- [Self-Healing / Recovery / Deployment Safety](https://banes-lab.com/ontology/principles/architecture-category-self-healing-recovery-deployment-safety.md)
- [Self-Healing / Recovery / Deployment Safety](https://banes-lab.com/ontology/lexicon/lexicon-category-self-healing-recovery-deployment-safety.md)
- [Severity levels](https://banes-lab.com/ontology/schema/the-vocabulary-severity.md)
- [The resolutions](https://banes-lab.com/ontology/schema/the-resolutions.md)