Wiktionary
vb. To automatically switch processing from a failed component in a critical system to its live spare or backup component.
Usage examples of "fail over".
Our charts are pitifully inadequate, our drives will probably fail over the long haul, and few ships our size have even taken transfer points successfully.
He was only sixty-five, but his health had begun to fail over the past few years, and he preferred viewing the world from his peaceful perch in Croton-on-Hudson.
Whenever I'm there, Hera and I fight then you go off and do one of those swan, shower of gold, quail things and we all know how that ends up Hera blames me since she can't seem to blame you, I get ticked off and crops fail over half of the southern hemisphere.
It is as if he is a reminder of something that is too elusive to grasp, something that is hurtful, even deadly, and in his presence we try to regain it and fail over and over.