1*80689db1SShawn McCarney# Phase Fault Monitoring 2*80689db1SShawn McCarney 3*80689db1SShawn McCarney## Overview 4*80689db1SShawn McCarney 5*80689db1SShawn McCarneySome voltage regulators contain redundant phases. If a redundant phase fails, 6*80689db1SShawn McCarneythe regulator can continue functioning normally. However redundancy has been 7*80689db1SShawn McCarneylost, and the regulator may fail if another phase fails. 8*80689db1SShawn McCarney 9*80689db1SShawn McCarneyVoltage regulators can be monitored for redundant phase faults. If a fault is 10*80689db1SShawn McCarneydetected, an error is logged on the BMC. 11*80689db1SShawn McCarney 12*80689db1SShawn McCarneyWhen [regulator monitoring](monitoring.md) is enabled, the `phosphor-regulators` 13*80689db1SShawn McCarneyapplication checks for redundant phase faults every 15 seconds. 14*80689db1SShawn McCarney 15*80689db1SShawn McCarneyA phase fault must be detected two consecutive times (15 seconds apart) before 16*80689db1SShawn McCarneyan error is logged. This provides "de-glitching" to ignore transient hardware 17*80689db1SShawn McCarneyproblems. 18*80689db1SShawn McCarney 19*80689db1SShawn McCarneyA phase fault error will only be logged for a regulator once per system boot. 20*80689db1SShawn McCarney 21*80689db1SShawn McCarney## How phase fault detection is defined 22*80689db1SShawn McCarney 23*80689db1SShawn McCarneyPhase fault detection is defined for a voltage regulator using the 24*80689db1SShawn McCarney[phase_fault_detection](config_file/phase_fault_detection.md) object in the 25*80689db1SShawn McCarney[JSON config file](config_file/README.md). 26*80689db1SShawn McCarney 27*80689db1SShawn McCarneyThis object specifies actions to run, such as 28*80689db1SShawn McCarney[i2c_compare_byte](config_file/i2c_compare_byte.md). 29*80689db1SShawn McCarney 30*80689db1SShawn McCarney## Error handling 31*80689db1SShawn McCarney 32*80689db1SShawn McCarneyIf a different type of error occurs while detecting phase faults in a regulator: 33*80689db1SShawn McCarney 34*80689db1SShawn McCarney- The error will be logged. If the same error occurs repeatedly on regulator, it 35*80689db1SShawn McCarney will only be logged once per system boot. 36*80689db1SShawn McCarney- Any remaining actions for the regulator will be skipped. 37*80689db1SShawn McCarney- Phase fault detection will continue with the next regulator. 38*80689db1SShawn McCarney- Phase fault detection will be attempted again for this regulator during the 39*80689db1SShawn McCarney next monitoring cycle. 40