Subruns

A subrun scheme is available in the MIDAS event logger utility (mlogger) to split a big data file into several individual data files. This feature might be helpful if a data file from a single run gets too large (>4 GB for example) and if shorter runs are not wanted for efficiency reasons. The scheme works as follows:

In the ODB /Logger/Channels/x/Settings/ subtree except where noted

• If a new subrun is to be started
  • after a certain time :
    • Set /Logger/Subrun duration key to the required time in seconds.
  • or after a certain number of bytes :
    • Set Subrun Byte limit key to the required number of bytes for the subrun

• Set Filename key to something like run%05d_%02d.mid. The first %05d will be replaced by the run number, while the second one will be replaced by the subrun number. This will result in files such as

   run00001_00.mid    run #1
   run00001_01.mid      "
   run00001_02.mid      "
   run00001_03.mid      "
   run00002_00.mid    run #2
   run00002_01.mid      "
   run00002_02.mid      "
   run00002_03.mid      "

Each subrun will contain an ODB dump if this is turned on via ODB Dump key. The stopping of the "main" run (after four subruns in the above example) can be done in the usual way (event limit in the front-end, manually through odbedit, etc.).

Note: the user may manually request a new subrun to start, set the Next subrun key to "y".