If you have a laptop with a optical disk drive, you can remove the drive and replace it with a second hard drive for backups alone. You can even make it a 1.5T

If you have a laptop with a optical disk drive, you can remove the drive and replace it with a second hard drive for backups alone. You can even make it a 1.5TB HDD and use something like Time Machine for multiple version backups that backup all the time. That way you don't have to carry anything. Most of your billable hours would be saved that way. I also have an external HDD connected to my laptop dock that does automatic backups whenever I connect the laptop to it, and I have crashplan for 'offsite' backups. I don't use my second HDD in my laptop as a backup hard drive although.