External storage

The external storage feature manages external storage volumes and make them available to system applications and protocols. The storage is used to store and retrieve data files when use pattern is such that external storage is the best choice. The feature supports network attached storage protocols: NFSv3, NFSv4, and SCP (sshfs).

One application of external storage is the saving and restoring of DHCP lease files over SCP or NFS network attached storage systems. SCP file system protocol uses a user mode process to emulate a network file system. The key advantage is packet level encryption and simple configuration. The key disadvantage is slow performance.

An admin sets up external storage volume credentials and then enables it. A storage management process acts on admin requests by enabling the storage volume using the requested storage protocol. An admin can disable the external storage volume or just set it up but leave it disable.

The feature maintains storage volume state. The states are: *disabled* (down), *connecting* (establishing connection), *operational* (up), and *unaccessible* (unavailable).

If a storage volume is unavailable, the system will attempt to reconnect periodically. Multiple volumes could connect concurrently - if one connection times out the others can connect right away.

The system supports server connection via data and management ports.

Data port support requires server IP address on a default or non-default VRF.

Once storage volume is enabled, applications can use the volume to store retrieve and delete files and directories.