The Integration Service creates temporary files when it sorts data. It stores them in a work directory. You can specify any directory on the Integration Service node to use as a work directory. By default, the Integration Service uses the value specified for the $PMTempDir service process variable.
When you partition a session with a Sorter transformation, you can specify a different work directory for each partition in the pipeline. To increase session performance, specify work directories on physically separate disks on the Integration Service nodes.