# NIST SP 800-53 Rev. 5 AU-5(1) — Storage Capacity Warning - Source: https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/au-5-1-storage-capacity-warning - Section: [Compliance](https://support.icompaas.com/compliance) › [NIST SP 800-53 Rev. 5 Controls](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5) › AU — Audit and Accountability - Last updated: 2026-06-05 - Publisher: iCompaas, Inc. (https://www.icompaas.com) **NIST SP 800-53 Rev. 5**·Control `AU-5(1)`·medium·Component: **Audit and Accountability** ## What this control requires > Warns personnel when audit log storage reaches a defined percentage of capacity, enabling proactive management of storage resources. This control supports the Storage Monitoring Tool capability within the Audit and Accountability family. > > — NIST SP 800-53 Rev. 5, Control AU-5(1) ### In plain English Warns personnel when audit log storage reaches a defined percentage of capacity, enabling proactive management of storage resources. In practice, this means you can prove you audit management-level controls on a defined cadence. ## Why it matters SP 800-53 is the catalogue every U.S. federal authorisation (FedRAMP, FISMA, CMMC) and most regulated industries point at. A missing control surfaces as a Plan of Action & Milestones (POA&M) item that an Authorizing Official must approve before the Authority To Operate is granted or renewed. ## What an auditor looks for A 3PAO (FedRAMP) or Independent Assessor (NIST RMF) tests against NIST SP 800-53A assessment procedures. For each control they expect a documented implementation that addresses every assessment objective (Examine, Interview, Test) and an implementation summary in the System Security Plan. Within **Audit and Accountability**, the assessor will trace your implementation back to the catalogue reference (Control AU-5(1)) and look for objective evidence on the latest two assessment cycles. ## How to implement #### Cloud Posture **CSPM.** Run Wiz / Prisma / Defender for Cloud / Security Command Center over every account; auto-ticket findings above your accepted-risk threshold. #### Configuration Management **Policy-as-code.** Codify the control as Service Control Policies (AWS), Azure Policy initiatives, or Organisation Policy (GCP) so the platform enforces what the document promises. **IaC.** Gate Terraform / Pulumi / CloudFormation changes with Checkov / tfsec / OPA so misconfigurations never reach production. **Drift.** Run a CSPM (Wiz / Prisma / Defender for Cloud / Security Command Center) over every account and route findings to a single risk register. #### Logging Monitoring **AWS.** Org-trail CloudTrail to a central log archive account, GuardDuty in every region, and Security Hub for cross-source correlation. **Azure.** Pipe every diagnostic setting into a central Log Analytics workspace; onboard Microsoft Sentinel for SIEM/SOAR. **GCP.** Aggregate audit logs in a dedicated logging project with sink to BigQuery; enable Security Command Center Premium and route findings to Chronicle SIEM. ### Operational checklist - **Audit.** Document the trigger, the owner and the cadence. - **Security.** Document the trigger, the owner and the cadence. - **Configuration.** Document the trigger, the owner and the cadence. - **Network.** Document the trigger, the owner and the cadence. - **Audit Log.** Document the trigger, the owner and the cadence. - **Scope:** management, personnel, storage capacity, configuration, capability, accountability, tool capability, resources. ## Evidence to collect - **Infra Scan.** Continuous infrastructure-posture telemetry — AWS Config, Azure Policy compliance, GCP Organisation Policy, Wiz / Prisma findings. Infrastructure posture tooling (AWS Config, Azure Policy, Nessus) verifies platform hardening. Focus: Storage Capacity Warning. ## Common pitfalls - Treating CSPM findings as a backlog instead of a hot queue: findings older than the policy SLA accumulate until the auditor asks why. - Manual cloud-console changes that never make it back to Terraform — drift accumulates until the next outage forces a reconciliation. - Per-account logging that nobody stitches together at the org level — incidents that cross accounts go undetected for days. - Default-allow egress rules; East-West traffic with no segmentation; jump hosts on the public internet with password auth. ## How it maps to other frameworks Computed from shared tags, control component and key-operation subjects — handy when you are reconciling controls across an audit. - [**BSI C5:2020 OPS-14** — Logging and Monitoring - Storage of the Logging Data](https://support.icompaas.com/compliance/bsi-c5-2020/ops-14-logging-and-monitoring-storage-of-the-logging-data) - [**NIST SP 800-171 Rev. 3 3.13.6** — Network Communications - Deny by Default - Allow by Exception](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-13-6-network-communications-deny-by-default-allow-by-exception) - [**CIS Controls v8 8.3** — Ensure Adequate Audit Log Storage](https://support.icompaas.com/compliance/cis-controls-v8/8-3-ensure-adequate-audit-log-storage) - [**ISO/IEC 27001:2022 A.5.34** — Privacy and protection of personal identifiable information (PII)](https://support.icompaas.com/compliance/iso-27001-2022/a-5-34-privacy-and-protection-of-personal-identifiable-information-pii) ## Related controls in NIST SP 800-53 Rev. 5 - [**Control AU-4** — Audit Log Storage Capacity](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/au-4-audit-log-storage-capacity) - [**Control AU-5(3)** — Configurable Traffic Volume Thresholds](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/au-5-3-configurable-traffic-volume-thresholds) - [**Control AU-9(7)** — Store On Component With Different Operating System](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/au-9-7-store-on-component-with-different-operating-system) - [**Control AU-11(1)** — Long-Term Retrieval Capability](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/au-11-1-long-term-retrieval-capability) - [**Control AU-4(1)** — Transfer To Alternate Storage](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/au-4-1-transfer-to-alternate-storage) - [**Control AU-6(5)** — Integrated Analysis Of Audit Records](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/au-6-5-integrated-analysis-of-audit-records) ## References - [NIST Computer Security Resource Center — NIST SP 800-53 Rev. 5](https://csrc.nist.gov/Projects/risk-management/sp800-53-controls) - Catalogue identifier: `Control AU-5(1)` Topics: logging monitoringcloud postureconfiguration managementnetwork security ## Related compliance guidance - [NIST SP 800-53 Rev. 5: a practical implementation guide for cloud teams](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5): Start with the full NIST SP 800-53 implementation guide — scope, roadmap, evidence and how the assessment runs. - [NIST SP 800-171 and CMMC: a practical guide to protecting CUI in the cloud](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3): If your obligation is protecting CUI in your own systems for a federal or defence contract, this derived subset — not the full catalogue — is the requirement. - [SOC 2 compliance: a practical implementation guide for cloud-native SaaS teams](https://support.icompaas.com/compliance/soc-2-trust-services-criteria): Most commercial SaaS already hold a SOC 2 Type 2, and FedRAMP 20x Class A is designed for providers that have one.