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1. Data acquisition - The online monitoring nodes get detector data over the network and place it in shared memory on each node. There is a set of monitoring nodes allocated for each instrument. The detector data are received over the network by snooping the multicast traffic between the DAQ readout nodes and the data cache layer. Analysis performed at this stage provides < 1 s feedback capabilities. The methods for doing (quasi) real time analysis are described in the Prompt Analysis page. Users should be aware of the different possibilities and choose the approach that works best for their experiment. 
2. Fast feedback - The processing nodes in the FFB system read the detector data from a dedicated, flash-based file system. It is possible to read the data as they are written to the FFB storage layer by the DAQ without waiting for the run to end.  Analysis performed at this stage provides < 5 min feedback capabilities. The resources reserved for this stage are described in the Fast Feedback System page.
3. Offline - The offline nodes read the detector data from disk. These systems include both interactive nodes and batch queues and are the main resource for doing data analysis. We currently support sending the data to three offline systems: psana, SDF and S3DF and NERSC. The psana system is the default offline system and your data will end up in psana unless you arrange a different destination with your experiment POC. The psana system is also relatively old and it will be retired when more storage becomes available in the SDF system. Please consider running at NERSC if you expect to have intensive computing requirements (> 1 PFLOPS).
    

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