The UPS and the diesel generator are 2 devices for keeping a server operational if there are difficulties with the primary power supply - a disruption or shaky current which cannot keep the hosting server working properly, for example. UPS is an abbreviation for Uninterruptible Power Supply, though it is sometimes called Uninterruptible Power Source also. The UPS is, in essence, an efficient battery which is attached to the web server and to the electricity network consistently, so if there is any disruption, it is already operating, which allows the web server to keep on doing the job without losing any data. The diesel generator is an engine which will power up a whole data center. It needs some time to start working and it is the UPS which gives it that time. These 2 power solutions are an absolute necessity for any facility or hosting company that wants to stop info loss and hardware damage caused by an unexpected electric power issue.