There appears to be some inconsistent use of tempfile.mkstemp() within upload.py that causes problems when users import data files to galaxy from a cluster directory via the upload process and import/temp/dataset directories are on different file systems. The issue manifests when Galaxy's job directory, dataset directory and import directory are on different file systems (common for cluster environments) in conjunction with a configuration where users can copy their data files directly to the import directory from which Galaxy selects data sets to upload (as opposed to using an FTP gateway). While allowing users to copy files to an import directory rather than using the FTP gateway may not be that common, we use this configuration locally to help build a more seamless interface with our local collection of HPC resources. Users can be logged into their cluster account and move data into galaxy with a file copy command rather than having to use FTP. This configuration has worked well in our environment as long as the correct ownership configuration existed on the import directory and as long as the import directory, job temporary directory, and galaxy data set directory were all on the same file system. We now have our galaxy dataset directory on a different file system and are seeing inconsistent behavior during the upload.py runs depending on if the data is ordinary text, BAM files, or gzipped data. A subset of uploads will fail because of the way temporary files are created by Galaxy to facilitate the import and any associated conversion processes of different file types. During the import, 1) Galaxy will copy the original file to a temporary target file (converting as needed during the copy). 2) Once this first conversion step is complete, Galaxy then attempts to move the temporary file back to the original location, ie. the import directory. 3) If this move is succeeds, Galaxy completes the upload processing and the data becomes a registered data set in the user's dataset collection. Galaxy prefers the Python shutil.move method to move tempfile . This results in a simple os.rename if the files remain on the same file system. However, if os.rename raises OSError because a move was attempted across a file system boundary, shutil.move resorts to a copy2, which copies the data to the original import file and then tries to copy the file attributes (permissions and utimes) to the original import file from the source file (which will be the temporary file Galaxy created in step 1 to begin the conversion process). The os.rename and shutil.copy2 behave (and fail) differently depending on the file ownership of the original import file. The os.rename will succeed even if the Galaxy upload.py job process only maps to the group-owner of the original import file (which can be ensured with group sticky bit on the import dir or ACLs). The shutil.copy2 command, however, will fail if the Galaxy upload.py job process UID is not the user-owner of the original import file. We could ensure the os.rename succeeds by keeping the job temporary directory and the import directory on the same file system. However, it seems the temporary directories used by upload.py are inconsistent across data types which prevents this simple fix from working for all data types. When text files are imported, upload calls the sniff.* methods to perform conversion. These methods use a bare call to tempfile.mkstemp() which ensures the file is created in the directory specified by the env var $TMPDIR. For example in sniff.convert_newlines: fd, temp_name = tempfile.mkstemp() https://bitbucket.org/galaxy/galaxy-central/src/5884328e91724e9bdf4b43f012eb... However, for compressed files, the upload.py script directly creates temp files but here it specifies the target directory as the same as the data set directory: fd, uncompressed = tempfile.mkstemp( prefix='data_id_%s_upload_gunzip_' % dataset.dataset_id, dir=os.path.dirname( output_path ), text=False ) https://bitbucket.org/galaxy/galaxy-central/src/5884328e91724e9bdf4b43f012eb... It's not clear if there is any significance to using the data set directory as the tempdir for compressed files versus the job temporary directory for other data files. It seems like all temporary files created by upload.py should be consistently created in the same temporary location, and preferably in the job temp directory. Is there a reason that these file types use different temporary file locations? If they used the same tempfile location, we could use one consistent system configuration and ensure all our data files can be imported even when the import+tempdir are not on the same file system as the Galaxy dataset dir. It seems reasonable that all tempfile.mkstemp() calls should be unadorned and inherit the temp directory location from their environment. A more comprehensive solution that would correct the inconsistency in failures between os.rename and shutil.copy2 and also remove any constraint for Galaxy to have it's import, temp, and data set directories on the same file system, would be to simply delete the original import file before attempting the shutil.move. This would ensure the file that the upload.py job attempts to create in step 2 is new and created with full Galaxy process ownership. Finally, it seems odd that Galaxy attempts to reuse the users original import file in the first place. It seems that once galaxy begins processing the content of the to-be-imported file, it should not ever write back to that file. What's the motivation here? I'll be interested to learn more about the motivations of these different tempfile conventions and if this can be fixed in the upstream. Thanks, ~jpr