Symmetrical Clock Checker Mechanism for High Availability Systems
Original Publication Date: 2000-Mar-01
Included in the Prior Art Database: 2003-Jun-18
Disclosed is a symmetrical clock failure detection mechanism that is located in two different clock subsystems (the first one being clocked by CLK_X and the second one being clocked by CLK_Y) and that is fed by both clock sources (CLK_X and CLK_Y). After agreement between both subsystems on which is the active and which is the back-up, each mechanism (Figure) continuously compares clock sources coming from its own subsystem and from the other one. If the back-up subsystem detects a clock failure, it deactivates the active one and takes the hand over by becoming the new active subsystem. An interrupt (CLK_MISS) is sent to a centralized ressource to indicate that the back-up subsystem must be replaced. If the active subsystem detects a clock failure, an interrupt (CLK_MISS) is sent to a centralized resource to indicate that the back-up subsystem must be replaced.