Time Machine backup of an external drive (to another external drive) I back up my internal drive to an external backup drive using Time Machine. I would also like to back up a 1TB external drive of mine, to another 1TB external drive of mine.

Is it possible to make Time Machine-styled backups of my external drive to the other external drive?

By Time Machine-style backups, I mean the way that Time Machine makes easy-to-browse "snapshots" on the backup drive, where you can view the source drive at different times by accessing different folders on the backup drive. 

I considered two ways to achieve this:


rsync using the --backup option


This moves all deleted files into a separate backup directory wherein it preserves the original file structure. Good, but not exactly the Time Machine styled backups I'm looking for. 
This also (to my knowledge) won't work for finding old versions of editing files. 

Carbon Copy Cleaner


This has the disadvantage again—all the deleted (and I believe modified files) are moved to a "safety net" directory. 



However, neither of them achieve the "browse different snapshots" behavior, à la Time Machine that I'm looking for. 

Is there any way to achieve what I'm requesting? 

I realize that it's possible with Time Machine itself, but from what I understand, it will only back the external disk up to my main backup disk. I want the external disk to backup to a secondary backup disk, keeping these backups separate from each other, mainly due to space limitations.
I have finally found the perfect answer to this. Behold the aptly-named rsync-time-backup project on GitHub. This is an easy-to-use bash script which can back up a source folder to a destination folder. Each backup made will create a time-labeled folder in the destination directory containing a full mirror of the source folder at that time, à la Time Machine.