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NOTE: Silo will be decommissioned April 1, 2017; with limited access and decreased performance after December 31, 2016 until the migration process is complete. Contact for more information.

Silo is a primary storage facility at WestGrid with over 3.15 PB (3150 TB) of spinning disk. It is an archival facility, which means that you should use Silo to store valuable data that you are not actively using for computation. Unlike most other WestGrid systems, some of the data on Silo is backed up.

There are two main login servers: Silo and Hopper.  Silo should be used for most regular file and data transfers.  Hopper is configured to allow some additional data processing.  Silo and Hopper share filesystems, so all files that are available on Silo are also on Hopper.


Silo is for file and data transfer.  Direct login access is via ssh to  The shell on Silo is restricted; it can only be used for managing and downloading files. You cannot run programs or scripts on Silo. For large file transfers, accessing the storage facility via Silo will give you the best performance.

To see a list of available commands on Silo that are permitted by the restricted shell, issue the command

ls /usr/local/rbin


Hopper is a processing node for the storage facility. Direct login access is via ssh to   No shell restrictions exist on Hopper. All the files that are accessible on Silo are accessible on Hopper as well: Silo and Hopper share filesystems. If you wish to do complex operations on files, including editing and running scripts, use Hopper.  Note that Hopper is intended for moderate data post-processing, not compute-intensive work.  It is a single server with a modest number of cores and amount of RAM.  If there extensive computation required, please use one of the many computational clusters/systems within WestGrid.

Transfers can be initiated via gcp, scp, sftp, or grid-tools, e.g., globus-url-copy, or Globus Online.  For large file transfers, accessing the storage facility via Silo (rather than Hopper) will give you the best performance.  However, transfers can be initiated to either Silo or Hopper using the above set of tools.


For best performance when copying large amounts of data to the storage facility from another WestGrid machine, use gcp (not scp) to Silo, or use the Globus Online tools.  

There are two main types of filesystems on Silo/Hopper:  those that are backed up to tape, and those that are not.  Filesystems beginning with /home are backed up to tape, while filesystems beginning with /data are not.


Space in /home on Silo is available for every user by default. /home is a GPFS filesystem. Because the data in /home is backed up to tape, it is somewhat more expensive storage space than /data.

For data in /home, direct incremental backups from the storage array at the UofS will be performed frequently (every 2-3 days, or nightly if total backup load allows). WestGrid makes no guarantees that any file can be recovered, regardless of where a file is stored. Best effort will be made to ensure reliability for all researcher data. WestGrid gives no guarantee regarding the security of data. Although every effort is made to ensure data is not compromised, there is no recovery procedure in place for major disaster (e.g. Acts of God).


These are directories into which a user stores files that they could, in an emergency, regenerate by other means. In the rare case of damage to the disk system, these files could not be recovered from the storage facility.
This is a good place to store data that meets one or more of the following criteria:

  • Large files that would be convenient to keep but can be re-downloaded. 
  • Large files that can be recreated or regenerated relatively easily.
  • Intermediate results of computation which need to be preserved for a short to medium length of time (as distinct from /scratch or /tmp on clusters).

Storage Information on Silo

Directory path Size Quota Command to check quota Purpose Backup Policy
/home 500GB (default) quota

Storing data requiring tape backup.

Backed up to tape. Retention period for deleted files: 45 days. Number of retained version of the same filename: 3.

/data 1000GB quota

Storing data not requiring backup.

No tape backup-0 copies kept. Retention period for deleted files: 0 days. Number of retained versions of the same filename: 0.