Patent ID: 8132038

Claim:
A computer program product for calibrating a Time Of Day (TOD)-clock in a computing system node provided in a multi-node network, said network comprising an infrastructure of computing devices each having a physical clock providing a time base for executing operations that is stepped to a common oscillator, the computer program product comprising computer usable medium having computer usable program code embodied therewith, the computer usable program code comprising: computer usable program code configured for obtaining samples of timing values of a computing device in said network, said values including a physical clock value maintained at that device and a TOD-offset-aggregate value; computer usable program code configured for computing an oscillator skew value from said samples; computer usable program code configured for setting a fine steering rate value as equal to the opposite of the computed oscillator skew value; and, computer usable program code configured for utilizing said fine steering rate value to adjust said physical clock value and correct for potential oscillator skew errors occurring in the oscillator crystal at said computing device, wherein said TOD-offset-aggregate value comprises: a TOD-offset value component that is added to a physical clock value to obtain a basic machine TOD clock at that node, a primary reference time (PRT) offset value component, and a Coordinated Server Time (CST) offset value component maintained at a computing device at that node.