disk quotas
Beginning February 14th, 2001, we started using disk space quotas for home directories on allspice. Prior to this, disk space was frequently running out (usually when final projects were due), and students had trouble completing homework assignments and reading email. Now users get a disk quota based on the classes they have taken, and our disk space usage has become stable.
Below are some questions and answers about our quota system. If you have any additional questions about our quotas, please feel free to email local-staff.
- Why do we need quotas?
Even though we have been buying more disk-space to try and accommodate all the new students in our department, we're simply growing too fast as a department to realistically continue with the previous policy of disk usage. Disk space is a finite resource, and we want to make sure that it's managed fairly and as efficiently as we can. Last semester, for example, there were a few occasions where one of the disks on which home directories are stored filled up, much to the chagrin of half the students of the department! So, we'd like to keep that from happening again. :)
- Okay, how much space do I get?
That depends on which courses you're taking. Some courses are much more disk-intensive than others--and it wouldn't be fair to hold everyone to the same standards if they had different needs. So, we've made a system of three tiers, separating the courses by how much disk space they typically require. To find out which quota applies to you, find the course with the highest tier that you've taken, and that's how much space you get!Tier I (30MB) - Non disk-intensive courses
CS 21, 22, 23, 25, 37, 41, 46
Tier II (60MB) - Slightly more disk-intensive courses
CS 35, 43, 44, 45, 63, 75, 85, 91, 93
Tier III (90MB) - The Biggun's
CS 27, 40, 65, 81, 97
- What happens if I use up more space than my quota?
These quotas are what we call "soft" quotas. That is, there won't be a big horned daemon to crawl out from the server room and devour you if you go over (we're working on that, just a few contract details, eheh...). You'll just get a little message when you log in informing you that you're over quota, and you'll be asked to clean up your directories (See "How can I lower my disk usage?"). We do, however, have a "hard" quota, which if reached will not allow you to write any more until you clear up some space. Also, if you remain above your soft quota for more than a few days, it will turn into a hard quota, and you'll be prevented from writing anymore to disk until you tidy up a bit.
- How do I know how much disk space I'm already using?
From the command line, type
du -sk /home/yourusernamehere
and this will tell you how many kilobytes of space you're currently using. Divide that number by 1024 (1024 kb = 1 mb), and bingo, that's your current disk usage.
You can also type quota to see your current quota information.
- How can I lower my disk usage?
The first thing we recommend doing is running a script we wrote to find your largest directories and largest files. Type dsu at the command line, and you should get a listing of your top 5 largest directories and your top 7 largest files. Examine these files and directories, and see if there is anything there that can be deleted.
Quite often your largest directory is a browser's Cache directory. If you have more than 5-10MB of cache files for one of your browsers (like mozilla or firefox), that will probably put you over quota. One way to remove the cache files is to start the browser, go into either Edit->Preferences or Tools->Options and look for Cache preferences. You should be able to both clear the current cache and set a limit on any future cache (I think the default is set to 20MB, which is too high).
Other things you can do to preserve space include removing old core files (left over from crashed programs), tarring and bzipping directories and files that you're not currently using, deleting any object files (*.o or *.a) and any extra backup files that editors like emacs and jove like to leave around (ones that end in '~' or start with '#'). Also, if you're starting to fill up on space, you should consider removing any files that aren't cs related, as you most certainly have your own cpu (or an sccs account or your student folder) for that kind of stuff.
- But I HAVE to do this project and it takes up more than my quota!
Fear not. If you need temporary storage space, temporary storage space you can get! Just cd into /local on any of the cs machines. You can make a directory and plop whatever it is that you need in there. However, we *strongly* emphasize the word temporary for this space, as we do not back it up and will without hesitation delete stuff cluttering it up if it starts to fill.
- I'm taking Graphics and NLP, and I still haven't taken 97. When I get to 97, what
will I do if I really don't want to delete my old projects?
Talk to us if you've taken a lot of storage intensive classes. It might be possible to further increase your quota.