An Investigation into Transport Protocols and Data Transport ...

2.2. Analysis Methods 31
the data in order to increase collider efficiency.
2.2 Analysis Methods
The search for new exotic particles such as the Higgs boson becomes a statistical
study of the probabilities that a particular event occurs. As such,
large volumes of data must be generated in order to determine with high
confidence that these rare events do actually occur.
Also, Monte Carlo simulations must be produced in order to reduce statistical
errors to an acceptable level. Generally, the size of such datasets are
equivalent to that of the filtered data from the detector.
At present, a typical experiment will store all raw detector data centrally
in tape archives, from which the data will be staged to disk when required.
When an institute wishes to run analysis on a particular dataset, the data
is typically copied (replicated) from the central facility to that of the local
farm at the institute. Collaborating institutes on the experiment operate
more or less independently, in as much as should another institute also want
to analyse the same dataset, they will typically also replicate it to their local
facilities - unaware that an exact replica may be physically closer than that
at the detector.
Access patterns for datasets vary. Experimental data files typically have a
single creator from which the initial production period will last several weeks
and will be modified as new information is added. However, metadata is also
created, which describes the information about the experiment. This may
be created by multiple individuals and may be modified and or augmented
over time, even after the creation of the experimental data. The size of meta
data is typically smaller than that of the experimental data.