| ### Updating the Time Nonmonotonically Use the clock set command with the -abruptly option when you want to abruptly set the time for a server system. The clock set command with the -abruptly option immediately (nonmonotonically) changes the system clock setting to the specified time, rather than gradually (monotonically) adjusting the time. Note: Exercise caution when changing the system time abruptly. The abrupt adjustment of the time is appropriate at system startup or when the system clock is faulty and you identify and correct the problem. Changing the system time to a setting that falls outside the time intervals of the system's known servers causes DTS to declare the system faulty at the next synchronization. Because the clock set command is usually used to correct gross clock errors, it is likely that the time you specify for a given system will appear faulty to the system's known servers if the system and servers have the same epoch number. You can prevent the systems whose times you are changing from being declared faulty. Use the clock set command's -epoch option along with the -abruptly option to set the new time to isolate it from the other systems. You can then change the time and epoch for the other systems until all the systems once again share the same epoch. This process is useful in the rare case when the majority of servers in the network are faulty. In order to use the clock set command effectively, you must have temporary access to an accurate time reference. Such references can include the time signals that many standards organizations disseminate by radio or telephone. You can also use a clock that you have recently verified as accurate. (See Appendix C for a list of time reference sources.) Because it is a manually entered command that is used to modify an absolute time, the clock set command is not useful for small inaccuracy settings. The minimum reliable inaccuracy that you can achieve with the command is approximately 1 second. Human error and processing delays combine to make lower settings unreliable. For example, you enter the command and new time and then begin monitoring the reference. When you perceive that the reference has reached the desired time, you press <Return> to initiate the command. Your perception of the reference mark and your pressing of <Return> do not exactly coincide. Furthermore, once the command is initiated, DTS takes time to interpret and execute the command. The following example shows how to change both the time and epoch for a system: dcecp> clock set 1993-10-07-09:30:15.0000I01.0000 -abruptly -epoch 1 dcecp> ###