Data Logger: Difference between revisions

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The Midas data logger serves multiple purpose of logging.
The Midas data logger serves multiple purpose of logging.
# Its main task is to log experimental data to storage device[[Event_Filtering|(s)]] such as disk, tape, FTP.
# Its main task is to log experimental data to storage device[[Event_Filtering|(s)]] such as disk, tape, FTP with prior data compression.
# Serves the logging of the overall Midas system messages
# Serves the logging of the overall Midas system messages
# Collect and log the history events
# Collect and log the history events
# Can log special information to an external mySQL database
# Can log special information to an external mySQL database


logging System messages to a Message file or as message events
The associated utility handling this Data logging is the [[mlogger]]. It runs on the backend computer, receiving events from the buffer manager. It supports three type of storage devices so far, i.e.
logging Experimental data to storage device(s) such as disk or tape
# Disk,
Multiple Logging Channels can be defined
# Tape
several different storage devices, formats and compression levels can be selected
# FTP channel to a remote computer.
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
logging information to a mySQL database
writing information to an electronic logbook
collecting and logging history events
When the MIDAS logger (mlogger) 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 /Logger tree contains all the relevant information for mlogger 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 /Logger tree to suitable values.


In addition to the /Logger tree, mlogger also creates the /History and /Elog ODB trees, used in the optional History and Electronic Logbook features. If MIDAS is compiled with mySQL support, a mySQL subtree will also be created in the /Logger tree (see Logging information to a mySQL database). All these features are described in the following pages.
The data channels as well as the history logging are rescanned automatically at each start transition. In other words, additional logging channels can be defined while running, but the effect will take place only at the following start transition.
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 :
Data can currently be written in five different formats :
* MIDAS binary,
* ASCII,
* ROOT
* DUMP


MIDAS binary,
A built in compression (gzip) can be enabled
ASCII,
ROOT
DUMP
The user may of course write their own custom data logger to save the data in any format they choose.
 
 
 
 
** [[Data storage options      → '' ''
** [[data compression]]      → ''''
** [[lazylogger|Secondary data logging]] (lazylogger)     → ''''

Revision as of 17:59, 15 February 2014

The Midas data logger serves multiple purpose of logging.

  1. Its main task is to log experimental data to storage device(s) such as disk, tape, FTP with prior data compression.
  2. Serves the logging of the overall Midas system messages
  3. Collect and log the history events
  4. Can log special information to an external mySQL database

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

  1. Disk,
  2. Tape
  3. FTP channel to a remote computer.

Data can currently be written in five different formats :

  • MIDAS binary,
  • ASCII,
  • ROOT
  • DUMP

A built in compression (gzip) can be enabled

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