Mass Storage – Common FAQs

What is Mass Storage?

Mass Storage services are available for the long-term archiving of important research data files that will be accessed infrequently. If you are interested in backing up your hard drive, go to the UNC Data Backup Options page instead. Only faculty, staff and graduate students may use the UNC Research Computing Mass Storage service.

How do I get access to Mass Storage service?

Access to the UNC Research Computing Mass Storage tape archival service is limited to users with accounts on a UNC Research Computing cluster.  Be sure to read and understand the intended use of the Mass Storage system, the Appropriate Use Policy and Things to Avoid before subscribing to tape archival service.

As long as you have a subscription on one of the UNC Research Computing clusters, you have access to Mass Storage services. To subscribe to a service, submit a request for the desired cluster using the form Onyen Services web page. Once you receive the email welcoming you to the Research Computing cluster, you may connect to the cluster and see your mass storage directory using the ms/ link from your home directory.

Is there a limit for Mass Storage?

Yes.  Mass Storage is limited; if you will be storing more than 10 Terabytes of data, you will need to contact Research Computing group ( ) to arrange to purchase tapes for your data.  For more information, please see “More on Mass Storage” line below.

Why can’t I open my files put on Mass Storage?

When you open a file in your ~/ms directory that has not been used for a while it may appear your task is hung.

Here is the reason.  The data is not in the disk cache.  The Mass Storage system is working to bring all the data on line from tape to disk.  Some clients keep silent about it, some may display a message such as “File temporarily unavailable on the server, retrying…”.

Here is what you need to do: Nothing.  Your process will resume once the data is available; usually a few seconds to minutes depending on size of the data.

How do I determine my disk usage on Mass Storage?

As mentioned previously, the amount of disk space available to users on Mass Storage is limited. In order to calculate current disk space usage, the “sdu” command can be used.  After switching to the ~/ms directory, entering “sdu” at the prompt will provide a listing of all disk usage for individual files and the total disk usage.  The “sdu” command will list total disk space usage on both the StorNext disk cache and in tape storage.  In contrast, the more common “du” command will only list information about files on disk cache and not in tape storage. The “sdu” command has access to metadata with regards to files on tape backup that is not available to the “du” command.  Use of the “sdu –h” command will produce output in a more easily readable format:

$ cd ~/ms
$ sdu -h

These commands can only be run on the Research Computing server login nodes.

Additional help

More on Mass Storage

Research Computing home page