/fs/junkfood is mounted on a RAIDed file server that features online snapshots of data from the past month. If you lose data that's been on /fs/junkfood long enough to get backed up, you can grab an old copy yourself, without waiting for the systems staff to locate, load, and restore the data from tape.
For example, say you delete your thesis, ~/thesis/thesis.ps, or /fs/junkfood/username/thesis/thesis.ps.
Go the top of your home directory:
[ringding 38] cd ~
Go to the backup directory:
[ringding 39] cd .zfs/snapshot
Choose the backup you want:
[ringding 40] ls 20090722140001 20090810220000 20090722220001 20090811140000 20090723140001 20090811220000 20090723220001 20090812140000 20090724140001 20090812220000 20090724220000 20090813140000 20090725210000 20090813220000 20090726210000 20090814140000 20090727140000 20090814220000 20090727220000 20090815210000 20090728140000 20090816210000 20090728220000 20090817140000 20090729140000 20090817220000 20090729220000 20090818140000 20090730140000 20090818220000 20090730220000 20090819140000 20090731140000 20090819220000 20090731220000 20090820140000 20090801210000 20090820220000 20090802210000 20090821140000 20090803140000 20090821220000 20090803220000 20090822210000 20090804140000 20090823210000 20090804220000 20090824140000 20090805140000 20090824220000 20090805220000 20090825140000 20090806140000 20090825220000 20090806220000 20090826140000
Each of these numbers is a directory with a copy of your home directory from a specific point in time. Each directory is named with the date and time that it was created, in the form YYYYMMDDHHMMSS (year-month-day-hour-minute-second).
So the directory 20090826140000 is from August 26 2009 (2009-08-26) at 2:00 pm (14:00:00).
Once you determine the correct directory to enter, simply cd into it and find your files.
[ringding 41] cd 20090826140000/thesis [ringding 42] ls -l -rw-r--r-- 1 bplecs 173305 Aug 21 20:06 thesis.ps
Now just copy it back:
[ringding 43] cp thesis.ps ~/thesis
The snapshot directories do not impact your quotas and are not writable.
Please note that /tmp directories on the junkfood machines are not backed up. Any data that is lost there either by accident or during boot-up when /tmp is cleared is lost forever.