You are equally likely to screw something up locally. I've had issues personally with backups working fine initially, but then as the system grows, I've run into hard limits imposed by the underlying technology: path length, bit rot, catalog size or corruption, memory limits, Windows locking files, etc. I used to backup servers to DVD's using dump/restore/bzip2, then found out that I couldn't restore after the compressed files exceeded 2 GB in size, because they couldn't be read back even though growisofs was happy to write them. I've run into quirks of all kinds with backup systems like Retrospect, Bacula, Genie Timeline, Cobian backup and others using both tape and hard drives. I've gone back and forth regarding whether a "push" or "pull" backup system is best, and still haven't made up my mind. It is really tricky to get right, and you usually don't find out you got it wrong until it's too late. Then it's reinstall everything, scrape what data you can out of the backup system, and back to the backup system drawing board.