I restarted the DAQ at 10:40PDT Tuesday morning to connect the EDCU to the new Beckhoff channels (PCAL at EX,EY, OMC renaming at C1). After the restart we noticed that the ALS_COMM guardian was stopped. The log file gives the error "no NDS servers available" at 10:40.

Looking into the code, the DOWN state of ALS_COMM calls the cdsutils.avg for the DAQ channel H1:ALS-C_TRX_A_LF_OUT_DQ to average this channel over 0.1 seconds. This NDS call failed when the DAQ was restarted and ALS_COMM remained stopped until a RELOAD was performed at a later time.

Looking at the guardian logs, two other systems have shown "no NDS servers available" errors: ISC_DOF and LSC_CONFIGS. In these cases they were not associated with an NDS restart, and were immediately followed by a guardian RELOAD (within a minute).