Mlogger: Difference between revisions

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==== Links ====
The midas documentation has moved. See [https://midas.triumf.ca/docs/develop/reference/reference/programs/#mlogger mlogger] on the Programs and options page and [https://midas.triumf.ca/docs/develop/features/storing_data/data_logging/ Data logging: overview] for the new documentation about the mlogger program.
<div style="column-count:4;-moz-column-count:4;-webkit-column-count:4">
* [[/Logger ODB tree| /Logger tree]]
* [[Keys in the ODB /Logger tree| /Logger keys]]
* [[Keys in the ODB /Logger/Channels subtree| /Logger/Channels keys]]
* [[Logging to a mySQL database]]
* [[Keys in the ODB /Logger/SQL subtree| /Logger/SQL keys]]
</div>
 
 
== Purpose ==
The purpose of <span style="color:darkcyan;">''mlogger''</span> is to save data from the experiment onto disk. See [[#Logging in MIDAS|logging in MIDAS]] for
a full list of what <span style="color:darkcyan;">''mlogger''</span> can do.
 
== Arguments ==
 
        [-e exptname ] :  experiment name (see [[Common Parameters to MIDAS Utilities]])
        [-D ] : start program as a daemon (UNIX only).
        [-s] : Save mode (debugging: protect ODB).
        [-v] : Verbose (not to be used in conjunction with -D).
        [-help ] : help
 
== Usage ==
 
    >mlogger -D
 
Notes
 
* The <span style="color:darkcyan;">''mlogger''</span> application requires an existing  [[/Equipment ODB tree]].
* When <span style="color:darkcyan;">''mlogger''</span>  is started for the first time, it creates the [[/Logger ODB tree|/Logger]], the [[/History ODB tree|/History]] and the[[/Elog ODB tree| /Elog]] ODB trees with default values.
* Once <span style="color:darkcyan;">''mlogger''</span> is running, you should be able to monitor its state with [[mstat]] or with [[mhttpd]].
 
=== Data storage location ===
If mlogger is started interactively (i.e. without the argument [-D ]) The following information will be displayed :
 
$ mlogger
Log    directory is  [[Keys in the ODB /Logger tree #/Logger/Data dir  |  <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 "!"
 
'''NOTE:'''
* To specify a Data directory different from the Log directory, use the Channels subtree [[Keys in the ODB /Logger/Channels subtree #/Logger/Channels/0/Settings/Filename | Filename key]]
* Different History and Elog directories may also be specified using the [[Keys in the ODB /Logger tree #/Logger/History dir | /Logger/History dir ]] and [[Keys in the ODB /Logger tree #/Logger/Elog dir | /Logger/Elog dir ]] keys respectively.
 
 
== Logging in MIDAS  ==
 
The MIDAS Logger, <span style="color:darkcyan;">''mlogger''</span> 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 to a mySQL database |logging information to a mySQL database]]
* writing information to an electronic logbook
* collecting and logging history events
* logging experimental data from one or more  [[Frontend Operation#Frontend|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 <span style="color:darkcyan;">''mlogger''</span>  utility runs on the backend computer, receiving events from the buffer manager. It supports three type of storage devices so far, i.e.
 
*    Disk,
*    FTP channel to a remote computer.
*    Tape (no longer maintained)
 
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.
 
=== mlogger creates ODB trees ===
When <span style="color:darkcyan;">''mlogger''</span> is started for the first time, it creates the [[/Logger ODB tree]] (including a single logger channel - channel 0), and fills it with default settings. The <span style="color:purple;">''/Logger''</span> tree contains all the relevant information for <span style="color:darkcyan;">''mlogger''</span> to run properly. The user has no code to write in order for the system to operate correctly. However, the user will want to customize the logger for his/her own experiment, by setting the keys in the <span style="color:purple;">''/Logger''</span>  tree to suitable values.
 
 
In addition to the <span style="color:purple;">''/Logger''</span>  tree, mlogger also creates the [[/History ODB tree]], used in the optional [[History System]] features. If MIDAS is compiled with mySQL support, a [[Keys in the ODB /Logger/SQL subtree |/Logger/SQL subtree]] will also be created in the <span style="color:purple;">''/Logger''</span> tree (see [[logging to a mySQL database]]).
 
[[Category:Utilities]]

Latest revision as of 22:01, 30 October 2026

The midas documentation has moved. See mlogger on the Programs and options page and Data logging: overview for the new documentation about the mlogger program.

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