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mlogger - MIDAS Logger

The MIDAS Logger, mlogger is supplied in the MIDAS package. This utility can perform several functions (selected by the user via the /Logger ODB tree ) including:

  • logging System messages to a Message file or as message events
  • logging information to a mySQL database
  • writing information to an electronic logbook
  • collecting and logging history events
  • logging experimental data from one or more frontends to storage device(s) such as disk or tape
  • multiple Logging Channels can be defined
  • several different storage devices, formats and compression levels can be selected
  • data can be logged to different subdirectories on disk
  • data can be logged to a remote computer, using the FTP mode
  • events can be selected for logging by Event ID or Trigger mask
  • Event Filtering can be implemented
  • runs can be automatically stopped and restarted after a certain number of events, or a certain time
  • the complete ODB contents can be saved
    • into a file at the beginning and/or end of run
    • and/or into the data stream

The mlogger utility runs on the backend computer, receiving events from the buffer manager. It supports three type of storage devices so far, i.e.

  • Disk,
  • Tape
  • FTP channel to a remote computer.

Data can currently be written in five different formats :

  • MIDAS binary,
  • ASCII,
  • ROOT
  • DUMP

The user may of course write their own custom data logger to save the data in any format they choose.

Starting mlogger utility

       [-h ] : help
       [-e exptname ] : experiment name (see odbedit - ODB Editor and run control utility)
       [-D ] : start program as a daemon (UNIX only).
       [-s] : Save mode (debugging: protect ODB).
       [-v] : Verbose (not to be used in conjunction with -D).
    >mlogger -D 


  • The mlogger application requires an existing /Equipment ODB tree.
  • When mlogger is started for the first time, it creates the /Logger, the /History and the /Elog ODB trees with default values.
  • Once mlogger is running, you should be able to monitor its state with mstat or with mhttpd.

Starting mlogger interactively

The following information will be displayed (providing mlogger has NOT been started as a daemon) :

$ mlogger
Log     directory is    <default directory>
Data    directory is same as Log unless specified in channels/
History directory is same as Log 
ELog    directory is same as Log 
MIDAS logger started. Stop with "!"