This allows you to configure the system to perform updates automatically. There are three steps to performing an upgrade, and you can select how many steps are performed automatically. The steps are described as follows:
Don't check for updates automatically - the  Search Appliance will not
  perform any actions on its own.Check for updates but don't download or install - the  Search Appliance
  will discovers whether software that is newer than what is installed is available.Download updates but don't install - the  Search Appliance will download
  software updates and hold them for you to peruse and install.Install updates automatically - the  Search Appliance automatically
  applies software updates as they're made available.