Last update: Apr 1, 2000
Speaker: Alessandra DoriaA simple and efficient mechanism to perform distributed online monitoring of detector, physics and data taking has been designed and implemented at KLOE.
Monitoring tasks, running on distributed nodes, are able to process online data without overloading the DAQ system and without unnecessary data transfer and duplication. This is accomplished using two types of connected daemons, namely ``spyd'' and ``remote spyd''. The former runs on the DAQ farm nodes and reads samples of formatted events directly from the buffers of the online data stream without interfering with the online farm processing. The latter runs on the machines used for monitoring, requests remotely spied events and makes them available to the local monitoring tasks.
The main monitoring tasks include event display, histogram producers, data quality indicators and trigger monitors based on fast event selection. The visualization of the monitoring results is performed by means of proper graphic facilities.
The system is largely flexible, since online monitoring tasks can be added as needed, with constraints only on network traffic and bandwidth.
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