John wants to know if a 512GB Thumb drive is big enough to back up his data. His hard drive is 93% full. Leo says it should be fine to move data over, but an external hard drive is much safer. Thumbdrive's can fail more often than hard drives. You can use a thumb drive, but make sure you have another backup of it. Can I back it up to Carbonite? Leo says that Carbonite doesn't back up external devices. Only your main hard drive. But he definitely agrees that John needs to get his data off that main drive. He needs at least 30% free for it to run properly.