Check out Clonezilla, which is the perfect tool for the job.

Thanks for pointing out dar, out definitely has some very interesting capabilities. My backup took off choice is BorgBackup as it makes local/remote, encrypted, deduplicated backups easy and allows for mounting previous snapshots via fuse fs for easy restore.

Instead of a fire safe which will only offer some protection I would rather get two Pelican style cases. Keep your backup drive(s) in there. Use a deduplicating/encrypted backup software to create two backup sets (I highly recommend BorgBackup). Store one of the backup cases off-site (at a friend’s house, in a drawer at work, …) and occasionally rotate the two cases.