dagsub:
* Restart DAGs will not work reliably unless pbs_server is configured to
  keep jobs for some period of time after they end (e.g. qmgr -c "set
  server keep_completed = 300").  Without this setting, dagsub is not
  able to determine whether or not a job completed successfully unless
  it happens to check while the completed job is in the 'E' state
  (which is typically only a few seconds).