If I Haven't Added Music, Should I Still Back up?

No, I would not repeat a backup if nothing had changed. You are probably increasing the chances of a problem with unnecessary backups.

For example, what if the main music drive had developed some corrupted files and you didn't know about the problem? In this case, you'd simply be wiping out a good backup copy and replacing it with the corrupted one.

If you're just worried about the condition of the backup drive, you can always run a disk integrity test on it

I keep two backups of my music drive and back those up only incrementally (i.e., only new music gets added. Existing song files are not replaced.) One of the backup drives is kept off-premises in the event of a fire, windstorm or theft at my home.

A word from Mr. Paranoid,

To answer your question no, you don’t need to back up data that has been previously backed up.

This might seem paranoid but I don’t let harddrives sit for extended lengths of time (months and months) without letting them spin up. I work in IT and I have heard techs talk about drives locking up after long periods of time on the shelf. Due to the mechanical nature of harddrives I tend to agree with this. So worst case, you stop collecting and your backup sits on a shelf for a few years. Then you have a crash. You're at the mercy of something mechanical that has been sitting.

I actually have 2 backups and keep one at work ... where I use it. The other sits on a shelf and every month or two I fire it up and do a “disk check”. I’m a PC person and run HD Tune which is a free utility that works well. There are plenty more free utilities and even tools built into the operating system to check drive integrity. The backup at home is pretty much a mirror of my main collection. The backup located at work is always a few months behind. I can’t tell you how many failures I have seen over the years ... drive prices have come down but so have the reliability of most of the drives. So my final backup rule is; every 5 years, I swap out the drives one at a time, even if everything is running perfect. So far it's been nice because as HD capacities have grown, I have managed to keep the entire collection on a single drive. I run Western Digital "black" drives but even with their high marks for reliability, I have experienced failures. About a year ago, I lost the drive that held the main collection. My backup was put to the test. Lucky for me; a 5 year warranty and an express return policy had me back up and running in less than a week.
The last rule of a backup system is to test it to see if it actually works …

PS - The flooding in Thailand has really caused drive prices to spin out of control. If you can wait 3-6 more months things are supposed to stabilize.

Thank you.

A good backup program will run periodicaly and only back up new or changed files automatically.

The Seagate USB drives I use came with a good backup program already installed that does this and works well. I'm sure there are others.