Check the docker container of image preview and image metadata, there was a 16GB .tif file under tmp folder. Py1 does not clean up the incomplete downloaded files if the downloading is not successful, but Py2 does that.
 

py1 code:

https://opensource.ncsa.illinois.edu/bitbucket/projects/CATS/repos/pyclowder/browse/pyclowder/extractors.py#803

py2 code:

https://opensource.ncsa.illinois.edu/bitbucket/projects/CATS/repos/pyclowder2/browse/pyclowder/files.py#56