Question: Time Machine backup of an external disk....?
Wondering how Time Machine handles if, except for the iMac's internal macOS disk, also an external disk is in the backup list? It seems to me that the macOS disk is being backup incrementally but that the external disk is being fully backed up each time... so no increments but full backup each time.
Is that observation correct? In that case why is that; it fills up backup space very fast of course?
iMac 27inch(late 2012) macOS 10.13.1, Fusion 1Tb macOs disk, 3Tb Lacie usb3 disk
iMac (27-inch, Late 2012), OS X Mountain Lion (10.8.5)