The UPS and the diesel generator are 2 devices for keeping a server working if there are problems with the main source - a disruption or unstable current that can't keep the web server working correctly, for example. UPS is an abbreviation for Uninterruptible Power Supply, even though it is sometimes referred to as Uninterruptible Power Source too. The UPS is, basically, an efficient battery which is attached to the machine and to the power network constantly, so in the event of any blackout, it's already operating, which enables the hosting server to continue operating without losing any information. The diesel generator is an engine that will power up an entire data center. It needs some time to begin working and it is the UPS that gives it this time. These two power solutions are an absolute necessity for any facility or hosting company that wants to prevent data loss and hardware damage caused by an unexpected power issue.