Hello, I have a request for help. I am trying to run some analysis code remotely through ssh in yt on NASA Pleiades. I have been able to install yt and trident and am running in a virtualenv, but something is having a very deeply buried error that I don't understand and fatally kills any task I send to Pleiades. The same code works fine on my home laptop with the same input files, so I assume the problem is something to do with the yt distribution on Pleiades, but I used "pip install -U yt" so it should be up-to-date. The error code comes from the fortran_utils file, and it says "unpack requires a string argument of length 4" (myenv) cstrawn@pfe27:~/quasarlines/quasarlines> python quasar_scan.py VELA_v2_08 10MpcBox_csf512_a0.330.d "[H I,H II,O IV,O V,O VI,Si II,Si III,Si IV,C I,C II,C III,C IV,Mg II,Mg III,Mg IV]" yt : [INFO ] 2017-07-25 12:11:26,454 discovered particle_data:/home1/cstrawn/quasarlines/quasarlines/PMcrs0a0.330.DAT yt : [INFO ] 2017-07-25 12:11:26,454 discovered particle_header:/home1/cstrawn/quasarlines/quasarlines/PMcrda0.330.DAT yt : [INFO ] 2017-07-25 12:11:26,462 Using root level of 14 yt : [INFO ] 2017-07-25 12:11:26,463 Discovered 7 species of particles yt : [INFO ] 2017-07-25 12:11:26,463 Particle populations: 28016640 4263936 752640 123904 19552 2089406 85309 yt : [INFO ] 2017-07-25 12:11:26,658 Max level is 12 yt : [INFO ] 2017-07-25 12:11:26,682 Parameters: current_time = 3.350407555 Gyr yt : [INFO ] 2017-07-25 12:11:26,682 Parameters: domain_dimensions = [128 128 128] yt : [INFO ] 2017-07-25 12:11:26,683 Parameters: domain_left_edge = [ 0. 0. 0.] yt : [INFO ] 2017-07-25 12:11:26,683 Parameters: domain_right_edge = [ 1. 1. 1.] yt : [INFO ] 2017-07-25 12:11:26,683 Parameters: cosmological_simulation = True yt : [INFO ] 2017-07-25 12:11:26,683 Parameters: current_redshift = 2.02694081565 yt : [INFO ] 2017-07-25 12:11:26,683 Parameters: omega_lambda = 0.730000019073 yt : [INFO ] 2017-07-25 12:11:26,684 Parameters: omega_matter = 0.270000010729 yt : [INFO ] 2017-07-25 12:11:26,684 Parameters: hubble_constant = 0.699999988079 18426 LOSs to scan. Is this an appropriate number? (0 for no) 1 1/18426 Traceback (most recent call last): File "quasar_scan.py", line 375, in <module> q.get_coldens(save = 10) File "quasar_scan.py", line 148, in get_coldens ftype='gas') File "/u/cstrawn/myenv/lib/python2.7/site-packages/trident/ray_generator.py", line 239, in make_simple_ray particle_type = _determine_particle_type_from_ftype(ds, ftype) File "/u/cstrawn/myenv/lib/python2.7/site-packages/trident/ray_generator.py", line 590, in _determine_particle_type_from_ftype field_list_arr = np.asarray(ds.derived_field_list) File "/u/cstrawn/myenv/lib/python2.7/site-packages/yt/data_objects/static_output.py", line 164, in ireq self.index File "/u/cstrawn/myenv/lib/python2.7/site-packages/yt/data_objects/static_output.py", line 419, in index self, dataset_type=self.dataset_type) File "/u/cstrawn/myenv/lib/python2.7/site-packages/yt/frontends/art/data_structures.py", line 65, in __init__ super(ARTIndex, self).__init__(ds, dataset_type) File "/u/cstrawn/myenv/lib/python2.7/site-packages/yt/geometry/geometry_handler.py", line 50, in __init__ self._setup_geometry() File "/u/cstrawn/myenv/lib/python2.7/site-packages/yt/geometry/oct_geometry_handler.py", line 25, in _setup_geometry self._initialize_oct_handler() File "/u/cstrawn/myenv/lib/python2.7/site-packages/yt/frontends/art/data_structures.py", line 91, in _initialize_oct_handler self.domains] File "/u/cstrawn/myenv/lib/python2.7/site-packages/yt/frontends/art/data_structures.py", line 761, in level_count self.level_offsets File "/u/cstrawn/myenv/lib/python2.7/site-packages/yt/frontends/art/data_structures.py", line 782, in level_offsets self.ds.min_level, self.ds.max_level) File "/u/cstrawn/myenv/lib/python2.7/site-packages/yt/frontends/art/data_structures.py", line 820, in _count_art_octs ns = fpu.peek_record_size(f, endian='>') File "/u/cstrawn/myenv/lib/python2.7/site-packages/yt/utilities/fortran_utils.py", line 250, in peek_record_size s = struct.unpack('>i', f.read(struct.calcsize('>i'))) struct.error: unpack requires a string argument of length 4 Please let me know if this is a known problem or if you have any idea what I should do to avoid running into it. I don't really understand fortran enough to know what is even supposed to be happening in fortran_utils. Thanks so much, Clayton Strawn