Quotas are enforced on a per user, per filesystem basis. It doesn't matter if a filesystem is located on a physical disk partition, a LVM LV or a RAID volume.
Edit your fstab and make sure your filesystem is mounted with the 'quota' option.
Run quotacheck on your filesystem to create the quota files.
Run edquota -f [filesystem] [username] to set use quota on filesystem.
--== Anything can go wrong. It's just a matter of how far wrong it will go till people think its right. ==--