In Time Machine one can back up to several drives at the same time. It is also possible to control which folders are backed up and which are not. However, it seems to me that the same folders have to be backed up to all drives.

Is it possible to exclude a folder from being backed up to one drive, while including it in the backup to another drive?

I use OS X 10.10.1.


I also believe Time Machine's GUI is not able to do that. But if you feel like fiddling in CLI from terminal, and do some basic scripting, it can be done quite easily using the tmutil command:

  • tmutil addexclusion and tmutil removeexclusion would allow to change your exclusion list by script whenever you want.
  • tmutil startbackup -destination would allow to trigger a backup by script to the desired destination, at the appropriate time (what about just after you changed your exclusion list? ;) )
  • script scheduling could be done using launchctl (or with a basic crontab job)

Of course, you should disable Time Machine in the Preference Pane, in order to prevent it from starting automatically while your scripted backup may be already running.

Bottom line, have a look at man tmutil. Backups would still be plain standard TimeMachine backups, just triggered differently. Restore could be done in GUI as usual.

Of course, if you have no previous experience in terminal mode or scripting, this gonna be a little harder. But if you feel like learning something geeky, this is the time to try (and then ask for help if needed!). ;-)

  • This would be the only way to implement such a change. It's really not that complicated and there are all sorts of apps that "schedule" Time Machine to only run once daily or nightly that use the tmutil call for such purposes quite reliably. – bmike Apr 8 '16 at 22:40
  • Wow, that's very interesting. But I'm afraid I have terminal phobia. I have actually used it a lot in GNU/Linux, even written some simple bash scripts. But the reason I switched to OS X is because I actually kinda dislike all that CLI stuff. – Revetahw says Reinstate Monica Apr 9 '16 at 2:12
  • Anyway your answer is impressive and I'm sure it would work. – Revetahw says Reinstate Monica Apr 9 '16 at 2:18
  • As bmike mentionned, some OSX apps exist to manage finner Time Machine scheduling. You may submit an enhancement request to some of these apps, asking to include a feature to enable/disable some exclusion based of the target backup disk. – CuriousFab Apr 11 '16 at 14:33

I believe this is beyond the intent and capability of Time Machine which is to provide simple backup for most users. Your more advanced needs will be better served by something like Carbon Copy Cloner.

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