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Storage Integration

Kubernetes can integrate with existing enterprise storage infrastructure using various protocols and interfaces. This allows you to leverage your existing storage investments while modernizing your applications with Kubernetes. Understanding different integration options helps you choose the right approach for your environment.

Why Storage Integration?

Many organizations have existing storage infrastructure that they want to use with Kubernetes:

  • Existing investments - Leverage existing storage systems
  • Enterprise features - Use storage system features (snapshots, replication, encryption)
  • Compliance - Meet compliance requirements with specific storage systems
  • Performance - Use high-performance storage systems optimized for your workloads
  • Familiarity - Continue using storage systems your team knows
graph TB A[Kubernetes Cluster] --> B[Storage Integration] B --> C[iSCSI] B --> D[NFS] B --> E[Fibre Channel] B --> F[CSI Drivers] C --> G[Block Storage] D --> H[File Storage] E --> I[Block Storage] F --> J[Modern Standard] style A fill:#e1f5ff style B fill:#fff4e1 style C fill:#e8f5e9 style D fill:#e8f5e9 style E fill:#e8f5e9 style F fill:#f3e5f5

Integration Approaches

1. Native Kubernetes Support

Some storage protocols have built-in support in Kubernetes (though many are deprecated in favor of CSI):

  • NFS - Network File System (still commonly used)
  • iSCSI - Internet Small Computer Systems Interface
  • Fibre Channel - Block storage protocol
  • GlusterFS - Distributed file system

Characteristics:

  • Built into Kubernetes (in-tree plugins)
  • Simple configuration
  • Many in-tree plugins are deprecated
  • Limited features compared to CSI

2. CSI Drivers

The modern approach is to use CSI drivers that provide integration with storage systems:

  • Vendor-specific CSI drivers - Provided by storage vendors
  • Protocol CSI drivers - Generic drivers for protocols (NFS, iSCSI)
  • Standard interface - Consistent API across storage systems

Characteristics:

  • Modern standard (CSI)
  • Vendor-maintained drivers
  • Feature-rich (snapshots, cloning, expansion)
  • Active development

Protocol Selection Guide

Choose the right protocol based on your needs:

graph TD A[Need Storage Integration?] --> B{Storage Type?} B -->|Block Storage| C{Network?} B -->|File Storage| D[Use NFS] C -->|Yes| E[Use iSCSI] C -->|No| F[Use Fibre Channel] D --> G[Multiple Pods<br/>ReadWriteMany] E --> H[Single Pod<br/>ReadWriteOnce] F --> H style A fill:#e1f5ff style D fill:#e8f5e9 style E fill:#fff4e1 style F fill:#f3e5f5

NFS (Network File System)

Best for:

  • File-based storage
  • Shared storage (ReadWriteMany)
  • Simple integration
  • Content distribution

Characteristics:

  • Network-based file storage
  • Supports ReadWriteMany access mode
  • Good for shared content
  • Standard protocol, widely supported

iSCSI (Internet Small Computer Systems Interface)

Best for:

  • Block storage over IP network
  • Existing iSCSI infrastructure
  • Performance-sensitive block workloads
  • Cost-effective block storage

Characteristics:

  • Block storage over TCP/IP
  • Single pod access (ReadWriteOnce)
  • Lower cost than Fibre Channel
  • Good performance over network

Fibre Channel

Best for:

  • High-performance block storage
  • Enterprise SAN environments
  • Latency-sensitive applications
  • Existing Fibre Channel infrastructure

Characteristics:

  • Dedicated network (FC fabric)
  • Highest performance
  • Most expensive
  • Enterprise-grade reliability

Integration Architecture

Here’s how storage integration typically works:

sequenceDiagram participant App as Application Pod participant K8s as Kubernetes participant Driver as Storage Driver/CSI participant Storage as Storage System App->>K8s: Request PVC K8s->>Driver: Provision volume Driver->>Storage: Create volume (via protocol) Storage->>Driver: Volume created Driver->>K8s: PV created App->>K8s: Mount PVC K8s->>Driver: Attach volume Driver->>Storage: Connect via protocol Storage->>Driver: Volume attached Driver->>App: Volume mounted

Integration Considerations

When integrating existing storage with Kubernetes:

Performance

  • Latency - Network storage has higher latency than local storage
  • Bandwidth - Network bandwidth limits throughput
  • Protocol overhead - Different protocols have different overhead
  • Distance - Storage distance affects latency

Availability

  • Single point of failure - Shared storage can be a SPOF
  • Replication - Consider storage-level replication
  • Backup - Integrate with storage backup systems
  • Disaster recovery - Plan for storage-level DR

Security

  • Authentication - Ensure proper authentication to storage
  • Encryption - Use encrypted connections (iSCSI with CHAP, NFS with Kerberos)
  • Network isolation - Isolate storage traffic
  • Access control - Limit which nodes/pods can access storage

Operations

  • Monitoring - Monitor storage performance and availability
  • Capacity management - Track storage usage
  • Maintenance - Plan for storage system maintenance
  • Documentation - Document integration details

Modern Approach: CSI Drivers

The recommended approach is to use CSI drivers for storage integration:

Advantages:

  • Standard interface
  • Vendor-maintained
  • Feature-rich (snapshots, cloning, expansion)
  • Active development and support
  • Works with any storage system

Example CSI drivers for integration:

  • NFS CSI driver
  • iSCSI CSI driver
  • Fibre Channel CSI driver (vendor-specific)
  • Storage vendor CSI drivers

Best Practices

  1. Use CSI drivers - Prefer CSI drivers over in-tree plugins
  2. Evaluate performance - Test performance in your environment
  3. Plan for high availability - Consider storage-level HA features
  4. Secure connections - Use encrypted connections and authentication
  5. Monitor integration - Monitor storage performance and availability
  6. Document configuration - Document storage integration details
  7. Test failover - Test storage failover and recovery procedures
  8. Consider costs - Understand storage costs and capacity planning

Topics

  • iSCSI - Internet Small Computer Systems Interface integration
  • NFS - Network File System integration
  • Fibre Channel - Fibre Channel storage integration

See Also