Hi, I had my old mac and I recently got a new one. I was wondering.....I keep my time machine backups of my old mac on an external 500GB hard drive...can I use the same external hard drive to keep the backups of the new mac?.
If yes, Is the time machine smart enough to know which one belongs to which laptop?.
Are there any other cons of doing this?
MacBook Pro Apple Silicon
I have some additional information which may be helpful. Speaking generally, using one external disk for two Time Machine backups would create a logistical nightmare. In that case I would either use two separate external disks or I would buy one which is large enough and then partition the disk into two partitions with different names. Then each Time Machine would backup its data to one of the partitions which would have been so designated. These days external disks are reasonably priced, so why not just buy two disks and make them dedicated to each Mac?
What kind of Mac is the old one. Is the new Mac a laptop?
The new backup scheme using APFS will not allow you to put two backups on the same drive unless you create an APFS volume for each (using Terminal) or partition the drive. There is no way the two backups could be commingled in any way.
If you keep the old Mac connected to the network, you can host one drive for the other to backup to over the WiFi. That way you don't have to hot-plug drives. If both are desktop Macs, it probably doesn't matter.
It is best to have more than one backup, so if you had independent drives for each, and a single drive that shared the other backups, I wouldn't be concerned with the "all the eggs in one basket" theory.
Would strongly suggest putting the Existing TM Backup Drive aside and in a Safe and Secure Place - like Safety Deposit Box of your Bank.
It can be used again at a later time to Restore individual important Personal Data.
Purchase a New Blank External Drive ( cheap these days ) and start a New TM Backup regimen on the New Computer.
The exiting TM Backup Drive for the Old Machine, if used on the New Computer, may be reformatted to the Newer Drive format ( APFS ) and the Olde Backups may be lost or not accessible for future restoring purposes
I think that's a bad idea because you are possibly going to create backups that can't be used with either machine. USB drives are dirt cheap these days (4tb for $100) and put the old drive away after importing your previous apps and data.
I can see where the files get comingled and Time Machine is unable to determine which files to restore.
time machine for 2 macbooks in 1 single external drive
