The instance of the appropriate TProofDataSetManager is
instantiated via the plugin manager; by default an instance
of TProofDataSetManagerFile
managing the <sandbox>/datasets
area is created. The directive 'Proof.DataSetManager' can be used to
modify the settings for TProofDataSetManagerFile or to load a
different dataset manager; for example, to '/pool/datasets' as area for
the dataset information, the following directive can be added to the
xrootd config file
xpd.putrc Proof.DataSetManager file dir:/pool/datasets