Many network server hardware vendors offer multiple power supplies in their network servers. These multiple power supplies (usually two or three) share the electrical load of the network server. With multiple power supplies installed, the failure of a single power supply does not bring down the network server. These multiple power supplies are usually hot swappable, meaning that a failed power supply can be removed and a new power supply can be inserted while the network server is running. This leads to zero downtime due to a power-supply failure.