I myself have been using the backup software BackupPC for almost a decade, and I started to backup our lab computers to a central backup server about two years ago. BackupPC supports deduplication and therefore much data can be stored on a couple of 2 TB drives.
I do offsite backups using BackupPC. The amount of data increases constantly so I need to add occasionally hard disks. Additionally I want the data to be encrypted, at least after powering off the system that is running the BackupPC application. So I decided to use logical volume management (LVM) and block device encryption (cryptsetup). The following steps were needed (on Ubuntu Feisty):
BackupPC seems to be a cool application. Except for the fact that it is not easy to start working with in the first place. I downloaded BackupPC-2.0.0.tar.gz and installed it into the directory /usr/local/backuppc. Then I executed the config.pl and answered all I could. The place where I want to backup my stuff is my second hard drive /dev/hdb5 which is formatted as reiserfs and mounted at /mnt/hdb. After the config script there was a new directory in /mnt/hdb: backuppc, which contained 6 other directories: conf, cpool, log, pc, pool and trash.