The UPS and the diesel generator are 2 devices for keeping a server functioning in case there are problems with the main power source - an interruption or unreliable current which cannot keep the machine working properly, for instance. UPS is an abbreviation for Uninterruptible Power Supply, although it is oftentimes referred to as Uninterruptible Power Source too. The UPS is, in simple terms, a highly effective battery that is attached to the web server and to the power network all the time, so in case of any disruption, it is already operating, which enables the web server to continue operating without losing any info. The diesel generator is an engine that can power up the entire data center. It needs some time to begin working and it's the UPS which provides this time. These two power solutions are an absolute necessity for any facility or service provider that wants to avoid information loss and hardware damage resulting from an unexpected electrical power problem.