Timemachine - Turn off "No Backup for X Days" for secondary Disk On my MacBook Air I use TimeMachine with two USB-Disks. (Latest El Capitan)

My primary disk is located at my house, the secondary at my parent's house.

As I am not always at my parents, this "No Backup for X Days" pops up daily:



Does anybody know a way, how I can disable the notification for the secondary disk while leaving the notification for the primary disk?

Thanks
Since the backup volume is offsite, you can simply remove it from the list in Time Machine settings whilst it's away from home. When you add it back, Time Machine will pick up the existing backup. That's what I always do myself.

As for performance, the first backup after adding the volume back has a longer preparation step (presumably for computing the diffs) but that also happens anyway after a few weeks when Time Machine stops maintaining the diffs as changes on the file system occur in real time.