Quotas

Cleaning Up Files in Home

Often if you cannot find where all your quota space has gone, it can be that "firefox" has too big a "cache" (a location where it stores files for quick access). You should start up "firefox" and then select:

Edit -> Preferences -> Advanced -> Network

and there you will find the "Offline Storage" field which you could reduce; a 1 megabyte cache is large enough for many people, but you can use a larger one if you have the room to spare in your quota. You should also click the "Clear Now" button to erase your current cache.

If you have large files that are not being accessed frequently then you can recover a fair amount of space by compressing them with "gzip". For example "gzip bigfile" produces a compressed "bigfile.gz". Then to access the original file you can use "gunzip bigfile.gz" to recreate "bigfile". "gzip" works especially well on PostScript files; at times the compressed file is less than 10% of the size of the original.

If you type "ls -sS1r" that will produce a listing of the files in your current directory preceeded by their size in blocks sorted with the largest files at the end. (If you use "ls -sS1raR ~" then you will get a recursive listing of all files in all subdirectories of your home directory, including ones that start with a "." which are normally not listed.)

Cleaning Up Files in Email_Home

If you are overquota on Email_Home then you may need to clean out old large messages. Many email clients (like "thunderbird") actually only transfer email messages to the "Trash" folder when you "Delete" them. You have to select "Empty Trash" (from the "File" menu in thunderbird, for example) or "Purge" (from our webmail interface, for example) to actually erase those files from the disk and reclaim the quota.

Many email clients save copies of outgoing messages in the "Sent" folder. This file can become very large if you have emailed large messages (often those containing attachments such as papers or pictures). If you do not need copies of these you may want to delete them or at least delete the attachments if you have copies of those on coxeter.

We have currently enabled spamfiltering to automatically delete messages from SuspectedSpam folders after 7 days (by default) and to automatically discard all messages with a very high probability of being spam. You can use:

spamfiltering showall

to check the status of these features and use:

spamfiltering autodelete on

and

spamfiltering autoexpire on

to turn them on if they are off. "spamfiltering help" gives more information.

Information About Disk Usage Quotas for Coxeter

To find out what your current disk space usage is, type:

quota

You will see something similar to:

Disk quotas for user <your_loginname> (uid UID):
Filesystem blocks quota limit grace files quota limit grace
/home 14216 50000 150000 517 0 0
Email_Home 24084 70000 270000 518 0 0

if you have not exceeded your quota. The "quota" is the maximum number of 1KB blocks that you can store permanently, the "limit" is the amount you are allowed to store during a "grace" period of one week when you go over quota.

You will see something similar to:

Disk quotas for user <your_loginname> (uid UID):
Filesystem blocks quota limit grace files quota limit grace
/home 52052* 50000 150000 6days 2214 0 0
Email_Home 24084 70000 270000 518 0 0

If you have exceeded your quota you will see something similar to:

Disk quotas for user <your_loginname> (uid UID):
Filesystem blocks quota limit grace files quota limit grace
/home 52052* 50000 150000 none 2214 0 0
Email_Home 24084 70000 270000 518 0 0

The "grace" period gives the amount of time left for you to get below "quota"; if you run out of time you can no longer create any new files or edit current ones until your "blocks" are below "quota" again. Note that trying to edit files when there is no time left can sometimes truncate the file to zero size, effectively erasing it, so it is important to clean up early.

Note also that if you hit the "limit" or run out of the grace time when over quota in "Email_Home" then you will not receive any more email. People sending you email will get a bounced message saying that your are overquota and that the mail was not delivered. The quota and limit are fairly high for that directory so that if you keep your mail usage below 5-10MB then this
should not be a problem. We do not currently have the resources to store large numbers of pictures or video on our systems. These files take a lot of space and unless they are directly related to mathematics should not be kept on our
systems.

When logging in, if you are over quota the system will print a message similar to the following:

Disk quotas for user <your_loginname> (uid UID):
In block grace period on home


or

Disk quotas for user <your_loginname> (uid UID):
Over block quota on home

as appropriate. If your overquota situation is on the email server "home" above will be replaced with "Email_Home".

Your current quota and usage will be printed as well and the following message will appear:

WARNING: If you stay overquota for longer than the grace period, you may not be able to log in or receive email. Type quotas for more information about being overquota.

Surviving When the Quota Limit is Reached (suggestions from an earlier system)

In most cases, the only way for a user to recover from over-quota conditions is to abort whatever activity is in progress on the filesystem that has reached its limit, remove sufficient files to bring the limit back below quota, and retry the failed program.

However, if a user is in the editor and a write fails because of an over quota situation, that is not a suitable course of action. It is most likely that initially attempting to write the file has truncated its previous contents, so if the editor is aborted without correctly writing the file, not only are the recent changes lost, but possibly much, or even all, of the contents that previously existed.

There are several possible safe exits for a user caught in this situation. He can use the editor ! shell escape command to examine his file space and remove surplus files. Alternatively, using csh(1), he can suspend the editor, remove some files, then resume it. A third possibility is to write the file to some other filesystem (we have the directory /scratch/today on coxeter for that purpose, type "scratchspace" for more information) where the user's quota has not been exceeded. Then after rectifying the quota situation, the file can be moved back to the filesystem it belongs on.