3.4 Analysis Guidelines

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Detailed Review status

Under construction - note that a part of this page is NOT based on any discussions or decisions, and the rest is unconfirmed

Goals of this page:

This page gives general guidelines on analysis workflow and methods.



All analysis in CMS is done within the CMSSW framework. It offers several possibilities as explained in the analysis and framework tutorial pages. This page sets the general guidelines which you should follow for any analysis you wish to publish.

Analysis Guidelines

Any analysis should be reproducible with data and software available to all CMS collaborators.

Availability of the Data

The input data of your analysis should be available to all CMS collaborators in the DBS/DLS browser.

Availability of the Software

You should make the software needed to reproduce the analysis results available to all CMS collaborators in the CMSSW cvs directory. in the release/ with a special tag/ in the analysis subsystems/ in the UserCode area? Any analysis software producing new persistent objects should be a CMSSW framework module.

You can do the final analysis applying simple cuts and thresholds with a program of your choice

How to run Analysis

You should run the analysis jobs in T2 centres using CRAB.

Where to store Data

You can store the output data of your analysis jobs in ...

Analysis Workflow

Here we summarize the functions of of different computing tiers and and their role with respect to the analysis work.

Details: WorkBookComputingModel


Tier-0 accepts RAW data from the detector and distributes the Primary Datasets in RECO and AOD format to T1's.

Details: WorkBookComputingModel#TierZero.

The T0 does not provide analysis resources and only operates scheduled activities.


At CERN, though logically separated from the T0 is the CMS-CAF (CERN Analysis Facility). The CAF offers services associated with T1 and T2 centers and performs latency critical, non-automated activities. The CAF is not needed for normal Tier0 operation; it is intended for short-term, high priority, human-operated calibration, physics validation and analysis. For example, the CAF would be used for very fast physics validation and analysis of the Express Stream (a subset of the data that is tagged by Online and then processed as quickly as possible).

At start-up, to make best use of resources, physics analysis groups may ask to have some work done at CAF. Each group will have 4-5 accounts.

Example use case:


Tier-1 sites will in general be used for large-scale, centrally organized activities and can provide data to and receive data from all Tier-2 sites.

Details: WorkBookComputingModel#TierOne

Requests for rereconstruction and skimming are made by the physics analysis groups.

NNN studies the request and makes the decisions for the priorities.

Example use case:


The Tier-2 sites provide:

  1. services for local communities
  2. grid-based analysis for the whole experiment (Tier-2 resources available to whole experiment through the grid)
  3. Monte Carlo simulation for the whole experiment

Example use case:

Information Sources

Review status

Reviewer/Editor and Date (copy from screen) Comments
CMSUserSupport - 11 Sep 2007 created page

Responsible: ResponsibleIndividual
Last reviewed by: YourName - date

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Topic revision: r9 - 2015-04-15 - FreyaBlekman



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