Storage
Overview
On CS computers, several storage options are available. We provide centralized user home directories. This space is backed up regularly to tape, and is shared by many users. As such, it is a limited resource that is at a premium.
Many machines also have surplus local disk which is appropriate for using as scratch space, but is not backed up, and should not be relied apon as being persistant. You can store files in /tmp and /var/tmp; /tmp is cleared out during each boot. Access to local disk will be faster than to home directories, due to the protocol overhead of network-attached storage. However, please be aware that data stored in /tmp or /var/tmp may well vanish unexpectedly for a variety of reasons. If the data's persistence is at all important to you, please email techstaff@cs.uchicago.edu and let us know how much space you require.
Etiquette
For non-persistent data, please use /tmp instead of /var/tmp. If you intend to store more than a small number of files in /tmp or /var/tmp, please create and use a subdirectory so that listing /tmp or /var/tmp does not become time-intensive.
Quotas
We limit home directory storage by per-user quotas. Our quotas are not in place to restrict users, but rather to control the growth rate of storage utilization, and to prevent a user from inconveniencing other users by filling up an entire disk partition. If you require a higher quota to support your academic activities, please email techstaff@cs.uchicago.edu and we will try to meet your needs.
Gauging Usage
Unix has several facilities for monitoring storage consumption. The primary utilities are the du, df, and quota commands. Below are examples of common usage.
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Show quota usage
$ quota Disk quotas for user narusso (uid 10549): Filesystem blocks quota limit grace files quota limit grace brahman.cs.uchicago.edu:/export/u1/narusso 10 50118 62647 0 0 0In this example, use narusso is using 10 kilobytes out of a 50118 kilobyte quota. The user narusso will be prevented from writing more data to disk when the usage reached the limit (62647 kilobytes) or stays above the quota (50118 kilobytes) for longer than the grace period (not specified above, though the column header is present, because narusso is not currently above 50118 kilobytes.
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Show the amount of data in a directory
$ du -sh /home/narusso/STUFF/ 1.3M /home/narusso/STUFF $ du -sk -- * .??* | sort -nr | head 7048 html 1292 STUFF 1076 cs 584 .netscape 332 .Mathematica 308 .mail 156 RCS 36 .pmdir 32 batch 20 .pinerc narusso@fast-mail:~$
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Show local disk usage
$ df -h -l Filesystem Size Used Avail Use% Mounted on /dev/hda1 16G 11G 4.6G 71% /
World-Writable File Policy
World-writable files are a security liability and will have the world-writable bit removed automatically. If you are trying to work with other users, see our documentation on collaboration. If you are trying to keep state with a CGI script running on our personal home page web server, you may write your data to /tmp (or use facilities like php session variables).
Appropriate Use Policy
CS computers are intended to primarily support academic activities and departmental research. Shared resources, such as disk space, cpu, memory, open files, processes, etc, must not be monopolised by any one person or project, and priority will be given to departmental academic and research activities.
It is unwise to store unlicensed intellectual property in your CS account. This violates the University's Acceptable Use Policy and could result in the revocation of your computing privileges.