It is a popular personal cloud solution and often referred as Dropbox replacement. It synchronizes your files to the private server. You can access your files globally from the ownCloud server via mobile and desktop apps.
You can add external storage to your ownCloud with Dropbox, SWIFT, FTPs, Google Docs, S3, external WebDAV servers and more. Enable the encryption app to encrypt data on external storage for improved security and privacy. They have tons of plugins available, like music players, photo galleries, and video players.