To set up a cron for the inbuilt hdp-manage to perform backups, follow these steps:

1. Login as superuser (password: superuser)
2. Type sudo -s
3. Enter the password from step 1 again
4. Type crontab -e
5. Below the line that is already present add the line for the backup command, at the required interval, like

      # m h dom mon dow command

      0 9 * * * sudo hdp-manage backup create

      (for the backup to be run at 9 AM everyday)

This will ensure that the backup is taken and stored in the /hdp/backups folder. 

You can then follow the instructions here to store the backup in an external location on your network