Can I use a 4TB external hard drive to back up three separate Macs, each having about 340gb stored on them?
If so, How do I keep them separate?
My hard drive seems to want to replace the first Mac's backup with the second's.
iMac, macOS 10.12
You can use the same drive and TM will keep them straight but like others have stated I would have a separate drive for each Mac.
+1, each machine should have it's own dedicated EHD. I (and many experienced users on these forums) prefer the OWC Mercury Elite Pro for doing TM backups and general external storage drives. These drives have a very long history of reliability, reasonable cost, great vendor support and ease of use.
That being said, once each Mac has its own EHD with Time Machine (the belt), you can use the 4TB with 3 partitions to have an *additional* TM backup for each computer that you bring out every week or two. (The suspenders).
Or use the three partitions to maintain bootable clones using Carbon Copy Cloner or SuperDuper!.
Welcome to the Apple Support Communities.
It is best practice to have a drive dedicated to each Mac. Here’s an excellent one sold by Apple: G-Technology G-DRIVE mobile USB-C Portable Hard Drive - Apple.
Jack
External Hard Drives
