Managing UNIX Disk Usage

UNIX computer accounts at USC have disk quota limits. There are two different disk quotas: one for the number of files within the account and one for overall disk usage.

If a user’s account usage approaches 90% of their disk quota, a warning message will be sent to the user. As a general rule, you should not wait to receive a notice before you start to maintain your disk space usage. Certain factors may preclude warning messages from being noticed, so you should be proactive about staying within the allowed limits, so as to keep from having problems at potentially inconvenient times.

What are the current disk quota limits?
How can I find out how much of my disk quota I’m using?
What do I do when I have reached 90% of my disk quota?
What do I do when I have reached the soft limit of my disk quota?
What do I do when I have reached the hard limit of my disk quota?
What if I need an increase in my disk quota?

What are the current disk quota limits?

Most accounts on ITS-maintained systems have a space quota of 50 MB and limit of 10,000 files. Both limits include the user’s home directory and any subsequent subdirectories.

Increases for student accounts for students in specific courses are valid for only ONE semester. If these files are not cleaned out before the quotas set back to normal, student users may find themselves well over their allowed limit.

How can I find out how much of my disk quota I’m using?

On aludra.usc.edu, your disk quota can be found by running the command ‘quota -v’ at the prompt while logged into your account’s host through a ssh or terminal connection. On mizar.usc.edu, the disk quota command is ‘squota -k ~’. The quota commands will display six pieces of information: your current disk quota–current usage (usage), soft limit (quota), and hard limit (limit)–and your current file quota usage–usage (files), soft limit (quota), and hard limit (limit).

Soft limits are the part of your quota that you may temporarily exceed. If you surpass the soft limit for your space or file quota, you will have seven days to drop back below quota. Once this time limit expires, or if you approach the hard limit, you will not be able to add or create new files on your account; you MUST move or remove files from your account and drop back below your set quota.

What do I do when I have reached 90+% of my disk quota?

At 90+% of your disk quota, you will still be able to perform normal file operations, but you should begin to clean up your account. Cleaning out your account may include deleting old files and directories, downloading files to your local machine, or compressing files to take less space.

Deleting old files and directories

Users may find that their accounts become cluttered with old files and directories over time. Instructions for removing files in the Unix environment can be found on the Unix Commands and Utilities page.

Note: Be careful when removing files or directories that begin with a period (i.e., .cshrc, .login, etc.) These are configuration files that may make certain applications unusable if removed.

Note: A number of Sun users working in CDE delete files by placing them in the Trash. If these files are not Shredded, they still remain in your account, in the .dt/Trash subdirectory. These files can be either moved through CDE or by removing the files in the Trash directory.

Downloading files to your local machine

Files can be transferred between the Unix system and your local machine through a number of FTP programs, either built into a user’s operating system or third-party (ie., Fetch, Filezilla). Once files are downloaded to your machine, they can be deleted from the Unix system, lowering your disk and file usage.

Instructions on using various FTP clients can be found on the FTP page.

Compressing files

Files that aren’t used very frequently can be compressed to take up less disk space using gzip, while several files and directories can be combined using tar and then compressed. Once compressed, files can be transferred to your local machine or stored on your account, depending on the amount of space necessary to be freed.

Instructions on how to use the gzip and tar programs can be found on the File Compression and Tar pages.

Note: Some files do not compress very well, such as image and some multimedia files. During compression or archiving, you must also have enough space to house the compressed or archived file as well, or the routines will fail.

What do I do when I have reached the soft limit of my disk quota?

Once you have reached the soft limit of your disk quota, a timer will be set, and will begin to count down. You have seven days immediately after you go over the soft limit to reduce your disk or file usage, depending on which quota is being violated, before you will not be able to create any new files.

If you are over your soft limit, you should follow the steps above for reducing your disk usage. Your ability to compress and archive your files, however, may be diminished if the utilities will cause you to go over your disk quota’s hard limit.

What do I do when I have reached the hard limit of my disk quota?

If the timer set by the soft limit violation expires, or you approach your disk quota’s hard limit, you will not be able to create new files in your account. This may cause you to not be able to log into Sun machines or run any programs that require writing to disk before starting, such as Pine.

If you have approached your hard limit, you must remove files and drop back below your quota before you can perform other file operations. It is possible, but NOT HIGHLY RECOMMENDED to use temporary space in /tmp as a limited repository for some files. Due to the inherent volatile nature of files in /tmp (they may be deleted without notice), this space should only be used as an absolute last resort, and only for a very brief period of time.

What if I need an increase in my disk quota?

If you find that you need an increase in either your disk quota, you will need to place a request with your department’s authorized signer.

Only authorized signers are able to make such requests. Please be prepared to justify the need for a quota increase.

Getting Additional Help

If you have any questions, or need specific instruction or advice, you can contact the ITS Customer Support Center.