Messages & Announcements

Maintenance is complete on Sandhills. Please let us know of any troubles using the cluster by sending email to hcc-support@unl.edu

This notice concerns a policy that affects all HCC machines and potentially all HCC users.

SUMMARY:

HCC is implementing a new automated file purge policy on the /work filesystem for all HCC machines. Starting August 1, 2016 (note: now Sept. 15, 2016) we will remove any files on /work which have not been accessed for at least 6 months. This will not affect the /home filesystems or the Attic storage system.

EXPLANATION:

The /work filesystem exists on each HCC machine for working files. It is not designed, or intended, for long term storage. The /work filesystem periodically is filled near capacity and this requires files to be deleted to keep the system as a whole available for ongoing use. To date, we have used a somewhat manual process of warning the user community and relying upon voluntary file removal. This is no longer sufficient due to the number of users and the number of accumulated files (e.g. Tusker is currently precariously close to going off-line due to /work being filled). The prior method will be augmented going forward with the automatic removal of all files that have not been accessed for over 6 months. Artificial activity to circumvent this policy will be considered misuse of the system. Longer term file storage is offered by HCC on Attic for an annual fee. This year, that fee has dropped from $100/TB/year to $60/TB/year.

TRANSITION:

This policy will be implemented first on Tusker since /work there is almost out of space. Crane and Sandhills will be implemented soon thereafter. For the near future, while possible, the file purging will be done reversibly. Files will moved from the users /work directory, but will be held temporarily in a weekly purge directory.

Users may see if they have any files scheduled to be deleted by logging in and using the commands
hcc-purge
to see a summary and
hcc-purge -l (l as in list)
to list the files scheduled to be purged.

hcc-purge
Prints the calling user and associated groups disk usage and file count for files that match the HCC purge policy.

hcc-purge -l
Uses the less pager utility to list the file paths for candidate purge files for the user.

The list can also be accessed at the following path:
/lustre/purge/current/${USER}.list

This is not an academic exercise. /work on Tusker is over 90% full; attempts to clear the filesystem with the former method have been unsuccessful.

SUPPORT:

With any change, some challenges will be encountered. Please contact hcc-support@unl.edu if you have concerns or need assistance moving your data to long term storage.

For details on how to check for files scheduled to be purged please see
https://hcc-docs.unl.edu/display/HCCDOC/Handling+Data .
For details concerning Attic storage please see
http://hcc.unl.edu/attic .
For details concerning transferring files please see
https://hcc-docs.unl.edu/display/HCCDOC/High-Speed+Data+Transfers .

Our intent is to remove the least valuable files from /work filesystems while enabling HCC systems to continue to be used by as many NU researchers as possible.

To minimize the impact to running jobs we are declaring a downtime for Sandhills to complete this work. We will use this maintenance window to update various software components across the cluster. The Sandhills login node will also be updated and will require users to log off. Users will be denied access to the Sandhills login node until the maintenance is completed.