Decoding program

Blocks comes in different streams. Most of the times you can find data blocks in the HRDL stream (on the pocc machines is under /Data/BLOCKS/HRDL-B/). If you don't know in witch stream the blocks come please ask to X. Cai or to a pocc-friend :-). However commonly the incoming blocks from JMDC can be found on /Data/BLOCKS/HRDL-@/xxxx/yyy (where @: stands for "A" or "B", depending of which HRDL server we are using; yyy is the block file number (it ranges from 000 to 999); xxxx is the directory name)

Block files are produced 1 per minute (if JMDC is alive). When the block number reaches 999 a new directory named xxxx+1 is created and the block number restarts from 0.

In block file you can find event blocks, calibration blocks, slowcontrol blocks, nothing, everything ...

The program able to produce usable information from Block files is called Decode. It's launched normally with a python script:

The default decoding options for this script are:

  • decode the calibration (if it is in the block)
  • select only events with a 3/4 ToF trigger
  • reconstruct only 1 over 50 events
  • reconstruct only the Tracker as a standalone detector (from raw clusters up to tracks)
  • produce monitoring histograms

from the ~/TrackerUser/Monitor you can execute the following phyton script -d -B /Data/BLOCKS/HRDL-B -f 0040/529 -l 0040/999

Where the -d is the daemon mode (you can see it working with the shell command ps), -B indicate the Blocks directory, -f is the first block to be scanned, -l is the last block. If the field -l is leaved blanck the scanner could reach the end of the produced blocks and waits for the incoming of new ones. Another similar script is, that is basically the same script but without the prescaling.

The scanning program will produce in the Output directory few files:

  • CalDB _1261365522.root: this file contains a calibration (can be viewed by MonitorUI)
  • 0040580_126136727_ErrReport.txt: this text file provides several important parameters (event size, trigger rate, recon status). It is very useful for data quality quick check.
  • 0040580_1261365727_recon.root: contains the DST of the block (pg-standalone reconstruction)
  • 0040580_1261365727_hmon.root: contains monitoring infos (can be viewed by MonitorUI)
  • 0040580_126136727_ErrReport.txt is a text file with the statistics and error counting

NB: Please check that almost one scanning program is working on the machine (ps aux | grep scan). If it is not launch it from the desired position.

NB2: Don't launch too many istances of the scanner, it's a CPU consumer program.

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Topic revision: r2 - 2010-08-17 - AlbertoOliva
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