An apparatus and method for a first computing element and a second computing
element
to execute in lockstep in a fault-tolerant server. In one embodiment, the first
computing element provides a first instruction to a communications link and the
second computing element provides a second instruction to a communications link.
In one embodiment, a first local input-output (I/O) subsystem and a second local
I/O subsystem are each in communication with the communications link. The first
and/or the second local I/O subsystem compare the first instruction and the second
instruction. In one embodiment, the first and second local I/O subsystems indicate
a fault of the first computing element or the second computing element. Such a
fault may be determined by a miscompare of the first instruction and the second instruction.
