XRootD Buffer

General Design

Note, the definitive source of data rate/volume numbers is in DUNE DocDB #1086. The extracted numbers below may become out of date.

• A few bits of info:
  • 230MB per readout (all 6 APAs, 5ms window)
  • Lossless compression: 4
  • File size will determine the number of parallel writes and vice versa
  • Nominal "max top instantaneous rate": 3GB/s
  • Nominal spill is 4.5s
  • Spill cycle: 22.5s
  • Nominal data in spill: 13.5GB
  • Nominal data out of spill: 13.5GB
  • Average sustained: 1.2GB/s
• A proposal for the online buffer:DUNE DocDB 1628

XROOTD-FTS Interface

Design Considerations

• ofs.notify can be set to send ASCII messages to a FIFO or a user app/script
• format and content of the message can be configured by the developer
• considerations for blocking of xrootd by the reader of the FIFO

Functionality

• Receive a notification and parse it
• Run a part or all of the metadata generation, write it to a JSON file
• Send a HTTP post to the F-FTS agent