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Center for High Throughput Computing

File Availability Options

Which Option is the Best for Your Files?

Meant For Input/Software File Sizes Output File Sizes Available for Jobs Running ... File Security Special Considerations
HTCondor file transfer basic file delivery and return; see size limits at right 0 - 100 MB per file; <500 MB total per job 0 - 4 GB total in CHTC, UW Grid, and OSG available to your jobs, on CHTC and beyond DO NOT USE for files in /mnt/gluster OR /squid
SQUID Web Proxy large input or software shared by many jobs 100 MB - 1 GB per shared file N/A in CHTC, UW Grid, and OSG files will be world-readable large files unique to individual jobs are better for Gluster
Gluster File Share largest software, input, and output 100 MB - TBs per unique file; 1GB - TBs per shared file 4 GB - TBs in only a portion of CHTC accessible ONLY to your jobs on specific CHTC servers special submit "Requirements"

HTCondor File Transfer

HTCondor file transfer is the standard solution for file portability, and is built in to HTCondor job scheduling. You can see HTCondor file transfer as introduced in our "Intro to Running HTCondor Jobs" and in the HTCondor Manual.


  1. Applicability
  2. Transferring Input Files
  3. Transferring Output Files

1. Applicability

Intended use:
Good for delivering any type of data to jobs, but with file-size limitations (see below). Remember that you can/should split up a large input file into many smaller files for cases where each job only needs a portion of the data. By default, the submit file "executable", "output", "error", and "log" files are ALWAYS transferred.
HTCondor's file transfer is robust and is available on ANY of CHTC's accessible HTC resources (including the UW Grid of campus pools, and the Open Science Grid).
Input File Limitations:
HTCondor's file transfer can cause issues for submit server performance when too many jobs are transferring too much data at the same time. Therefore, HTCondor file transfer is only good for input files up to ~20 MB per file IF the number of concurrently-queued jobs will be 100 or greater. Even when individual files are small, there are issues when the total amount of input data per-job approaches 500 MB. For cases beyond these limitations, one of our other CHTC file delivery methods should be used. Remember that creating a *.tar.gz file of directories and files can give your input and output data a useful amount of compression.
Output File Limitations:
Because jobs are less likely to be completing at the same time, total job output size of up to 1 GB will not cause submit server performance issues, but it's always advantageous to create a *.tar.gz file of all desired output before job completion (and to also delete the un-tar'd files so they are not also transferred back).
Data Security:
Files transferred with HTCondor transfer are owned by the job and protected by user permissions in the CHTC pool. When signaling your jobs to run on the UW Grid (Flocking) or the Open Science Grid (Glidein), your files will exist on someone else's computer only for the duration of each job. Please feel free to email us if you have data security concerns regarding HTCondor file transfer, as encryption options are available.

2. Transferring Input Files

Simply add the "transfer_input_files" line to your submit file, like so:

transfer_input_files = file1,../file2,/home/username/file3,dir1,dir2/

Note: By default, the submit file "executable", "output", and "error" files are ALWAYS transferred.


  • DO NOT use "transfer_input_files" for files within /squid or /mnt/gluster, as doing so will create severe performance issues for your jobs and those of other users. (Similarly, you should never submit jobs from within /squid or /mnt/gluster.)
  • Comma-separated files and directories to-be-transferred should be listed with a path relative to the submit directory, or can be listed with the absolute path(s), as shown above for "file3". The submit file "executable" is automatically transferred and does not need to be listed in "transfer_input_files".
  • All files that are transferred to a job will appear within the top of the working directory of the job, regardless of how they are arranged within directories on the submit server.
  • A whole directory and it's contents will be transferred when listed without the "/" after the directory name. When a directory is listed with the "/" after the directory name, only the directory contents will be transferred.
  • Jobs will be placed on hold by HTCondor if any of the files or directories do not exist (or if you have a typo).
  • See more about file transfer in the HTCondor Manual.

3. Transferring Output Files

HTCondor will automatically transfer back ALL new or modified files to the submit directory. This automatically includes the "output" and "error" files indicated in the submit file.


  • Output files transferred back to the submit server will appear in the initial submit directory of the job.
  • HTCondor does not automatically transfer back new directories. Therefore, it is a best practice to have your job(s) create a *.tar.gz file for desired output directories, so that the *.tar.gz file gets transferred AND so that it is compressed.
  • It is important to have your job remove all unwanted "new" files before job completion, so that these are NOT transferred back as perceived output. This includes files that have arrived in the job working directory via an alternate file delivery method.
  • It is possible to list only your desired output files by using "transfer_output_files" in the submit file; however, if you have a typo in a filename or if any of the files are not created during the job, the job will be placed on hold and ALL output lost (which can be a pain). Therefore, "transfer_output_files" should be used with caution, or for jobs that always first create these output files (perhaps empty), even if the job later exits early with an error.