The UPS and the diesel generator are 2 means for keeping a server functioning if there are troubles with the primary power source - an interruption or unreliable current that cannot keep the server functioning properly, for example. UPS is an abbreviation for Uninterruptible Power Supply, even though it is oftentimes referred to as Uninterruptible Power Source also. The UPS is, in simple terms, an efficient battery that's attached to the server and to the power network at all times, so in case of any disturbance, it is already functioning, which allows the server to continue running without losing any info. The diesel generator is an engine which will power up the entire data center. It does take some time to begin working and it's the UPS which provides that time. Those 2 power solutions are a necessity for any facility or hosting company that wants to stop information loss and hardware damage caused by an unexpected power problem.