1) Identify the workflow from the dm_workflow table, get the r_object_id of the workflow:
select r_object_id, object_name from dm_workflow where object_name = 'your work flow name'
2) Identify the notes that are carried by this workflow:
select r_note_id from dmi_package where r_workflow_id = ' the object id of the workflow'
3) Get the content id of each of those note ids returned:
select r_object_id from dmr_content where any parent_id = 'the note id'
4) Go to DA, Administration->Job Management->Administration, use the "GET_PATH" method to find out the path of the files which stores the comments