# Integrate external storage systems with CubeCOS

> Learn about external SAN and NAS storage integration in CubeCOS to host VM disks and images, optimize internal SDS usage, and support hybrid storage architectures.

## External storage overview {#external-storage-overview}

This section provides configuration guides for integrating external storage systems with the CubeCOS platform. This allows you to use your existing SAN and NAS infrastructure as the main environment for hosting virtual machine (VM) disks and images.

While CubeCOS features its own built-in distributed storage [SDS](../../configuration/node_roles/storage), many organizations prefer to incorporate their existing hardware to maximize previous investments. This hybrid architecture enables the internal SDS to focus on critical cluster data while external systems handle the primary VM and image workload.

## Hybrid storage architecture limitations {#hybrid-storage-architecture-limitations}

Since the internal SDS is no longer the sole host for all VM data, administrators can reduce its physical storage requirements. However, SDS is still required during the initial setup process to support the following core logic and critical services.

### Cluster service requiring internal SDS storage {#cluster-service-requiring-internal-sds-storage}

- First-time setup logic: The installation process requires local data disks to initialize and deploy the SDS layer.
- K3S (CSI driver): Powers authentication and other cluster-critical services through the k8s-volumes RBD pool.
- Cinder: Manages the mandatory cinder-volumes RBD pool.
- Glance: Hosts the Glance images RBD pool for virtual machine (VM) images.
- Nova: Provides ephemeral storage for virtual machines via the ephemeral-vms RBD pool.
- Manila: Operates as the default file sharing service.
- Swift (via RGW): Provides the default object storage service.
- CMP: Manages critical database backups.
- Ceph (Backup): Manages the volume-backups RBD pool for volume backup services.
- Cluster Service Storage: Utilizes /mnt/cephfs (CephFS) for persistent cluster service storage.

## External stroage integration process overview {#external-stroage-integration-process-overview}

This section is designed for administrators who wish to seamlessly unify their current Fibre Channel, iSCSI, or NFS systems, such as those from NetApp or Dell SC Series, with the CubeCOS ecosystem. This allows these external resources to work alongside the internal storage pool. Follow the steps below to validate your hardware's compatibility and configure this hybrid storage architecture.

- **External storage requirements (network/hardware):** Details the physical and network prerequisites, including:
  - Fibre Channel HBA specifications
  - iSCSI
  - Network isolation
  - Zoning configurations
- **Configure External Storages:** This section explains how you can modify OpenStack configuration files (`Cinder`, `Glance`, and `Manila`) to define storage backends and enable vendor-specific drivers.
- **Utilize external Storage Spaces:** Covers procedures for verifying connectivity using CLI tools (such as `systool` and `iscsiadm`), managing multipath devices, and validating storage availability for virtual machines.

## Quick links {#quick-links}