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/oss/en/nfs-quota-agent/overview

Quota Agent Overview

Physical storage quota enforcement mechanisms and design principles for NFS PVs.

Quota Agent Overview

NFS Quota Agent is a high-performance storage enforcement daemon bringing strict filesystem-level quotas to Kubernetes NFS PersistentVolumes.

Background & Motivation

  • Standard NFS Limitation: Standard NFS provisioners track requested storage (10Gi) only as Kubernetes metadata without enforcing physical disk limits on the underlying storage host.
  • Storage Exhaustion Risk: A single rogue workload writing unbounded data can exhaust shared NFS disks, crashing co-located services.
  • Solution: Leverages Linux kernel XFS Project Quotas (xfs_quota) to enforce byte-accurate hard limits per NFS subdirectory.

Key Features

  • XFS Project Quota Engine: Immutable Project IDs mapped to directories for kernel-enforced limits
  • gRPC & HTTP APIs: Low-latency RPC for CSI provisioners alongside REST management endpoints
  • QuotaPolicy CRD: Native Kubernetes declarative custom resource definitions
  • Prometheus Metrics: Real-time volume utilization, headroom, and quota violation alerts
  • Built-in Web UI: Responsive storage administration dashboard