Re: how to identify how large the home volume of users?
It's a lot of steps, haven't tried it myself, but from an old Fedora book here are some relevant commands and files to get you started. Instead of me typing out 2-3 pages from the book, why not get a good Fedora administration book?
repquota command -- quota reports on users (-u) or groups (-g) or file systems (-a)
quotaon -- activate quotas
edquota -- apply quota limits
/etc/fstab -- activate quota options -- must modify this file (and remount file system?)
Truthfulness is the main element of character.