New UNIX Home Disk

Gentle /home disk user.

Almost a year ago, the server for our /home disk failed. As an emergency measure, we rushed lnx156 into service. The disk quota system that had been in place was abandoned temporarily.

The old /home disk quota was 500 MBytes per user. This was implemented for two main reasons:

1. If a rogue process runs away and fills up or overloads the disk, all users will be severely impacted. Many jobs will fail and/or general system responsiveness for all users will be severely degraded.
2. Since the disk is backed up daily, excessive volume of files means excessive overhead. I.e. poor performance for the duration of the backup as well as increased expense in backup media.

We are about to implement a new, faster /home disk server. It will have quotas of 1 GByte per user for the reasons described above. You are receiving this message because your /home disk usage is greater than 1 GB. So, what are you to do?

In general, there are three types of disk space available.

1. The /home disk is for essential files like login scripts, browser preferences, source code, scripts, etc. It will be backed up daily and historical records will be kept.
2. Several styles of temporary disk space are available. These are intended for files that can easily be reproduced, like libraries and executables, and for working space. They are not backed up. Available to all are spaces like /cdat/tem, /cdat/tem2, and /nfs/acc/temp. Other temporary spaces are primarily designed for a particular project like /nfs/ilc/sim1,2, and 3 for CesrTA simulations, and /nfs/erl/sim for ERL users.
3. Finally, there are several user, group, and project specific file systems. Some of these are backed up daily, and most do not implement quotas. For example, all users have a 2GB UserDisk (please see https://wiki.lepp.cornell.edu/lepp/bin/view/Computing/UserDisk). In addition, many projects or groups have dedicated file systems for vital, but voluminous project or group specific data, like the final results of data analyses or simulations. Because this type of usage could easily run away, filling all available space, we only allow users with specific needs to access these disks. For example, accelerator users can be given access to the /nfs/acc/user disk. If you feel you need space on /nfs/acc/user or some other project or group-specific file system, contact your supervisor who will authorize your usage to the computer group. For the time being, no quotas are in place on most of these file systems, though we may be forced to implement generous quotas if the disk fills up too often or if backups become excessively burdensome.

In some cases, you may find that your Mozilla profiles are using a large amount of disk space. To clear some of this space and prevent them from using up more than necessary, please see FirefoxBrowser and TbirdProfiles (https://wiki.lepp.cornell.edu/lepp/bin/view/Computing/FirefoxBrowser and https://wiki.lepp.cornell.edu/lepp/bin/view/Computing/TbirdProfiles).

We ask that you reduce your /home disk usage below 1 GByte before the new server is implemented, and make use of temporary disk space and user, group, or project disk space. This will ease the transition to the new server, which will be announced and scheduled in the near future.

Your home disk usage can be analyzed using du or baobab. For example:

• du -hcsx ~/* ~/.*
• baobab ~/

In summary, any personal, group, or project data should be stored in user, project, or group file systems instead of the home filesystem. Please see DataStewardship (https://wiki.lepp.cornell.edu/lepp/bin/view/Computing/DataStewardship) for more information.