When I am backing up my MacBook pro to my external hard drive does it only add the files that are not on there already or does it copy another copy of the files already on the hard drive?
After the initial backup, it gets only the changes since the last backup. That's one reason a slow spinner HDD is recommended, it'll be slow the first time, but subsequent backups will be quite fast. Unless you made an enormous number of edits or additions. If you were to add, say, 50GB of new data, when it's backed up that will be slow again. But after that is added, you're back to backing up smaller changes only.
After the initial backup, it gets only the changes since the last backup. That's one reason a slow spinner HDD is recommended, it'll be slow the first time, but subsequent backups will be quite fast. Unless you made an enormous number of edits or additions. If you were to add, say, 50GB of new data, when it's backed up that will be slow again. But after that is added, you're back to backing up smaller changes only.
When I am backing up my macbook pro to my external hard drive does it only add the files that are not on there already or does it copy another copy of the files already on the hard drive?
