Q: Is Carbonite Backup flash drive that is connected to your computer?
Source: Creative Commons, Skadoit
A: Unfortunately, the current version of Carbonite backs up only files that reside on the permanent hard drives in your computer. This means you can not back up external hard drives or flash drives. However, if you need to save a file that is on your flash, just move this file to your computer.
MyPCBackup, another of our backup services highly rated online backup external hard drives and flash drives, free of charge. Make sure it is connected to your computer when performing backup and you're good to go! Mozy is also free, but states that it safeguard that readers who are "fixed", meaning that flash drives will not be saved.
In general, the best way to confirm saving files to your flash drive is to manually copy them to your computer. Then, when you make your next backup, those files must be saved!