Tonight I have performed a test of my backups, restoring a few files from CrashPlan. It really doesn't take very long to test that:
- Your data is being backed-up - check that data you have recently created (e.g. images you've recently edited, CDs you've just encoded) is in your backups;
- Your data is can be restored from backup - restore a sample of data from the backup; a few dozen files to make sure that they restore and are as expected (e.g. the MP3 file plays, the image opens, etc.).
Now would be an excellent time to test your backups. If you don't have then, CrashPlan is recommended by many.