Using iMac with external drive

[dcdunk]

So my 2011 Mac Mini bit the dust the other day and I ordered the 2017 iMac with a 256 GB SSD. The Mac Mini had about 460 of the 500 GB used up and I have that backed up on my external drive. I will be setting up my iMac as new and will be transferring the files that I want to the computer and accessing the rest from the external drive.

My question is this: how can I use my backup drive as both an external drive for my computer and as my Time Machine backup? Is it as simple as partitioning the external drive?

 

[kohlson]

You would want to partition it, otherwise TM may consume all of the available space, leaving you essentially no "working room" for you iMac data.

 

[ApfelKuchen]

I appreciate that you just spent a chunk of change, but considering your recent object lesson in the value of a backup, I suggest you spend the money on a new, separate external drive for Time Machine. You're going to want to backup the contents of the current external drive as well as the internal drive - while partitioning the external drive would allow you to add that data partition to the backup... how much space will you have left on the external when the dust settles?

 

[dwig]

... I suggest you spend the money on a new, separate external drive for Time Machine. You're going to want to backup the contents of the current external drive as well as the internal drive - while partitioning the external drive would allow you to add that data partition to the backup... how much space will you have left on the external when the dust settles?

Far and away a more import issue than size is that backing up one partition to another on the same drive hardware isn't a very good idea since a single hardware failure would destroy both the original data (partition A) and the backup (partition B).

 

[dcdunk]

I appreciate that you just spent a chunk of change, but considering your recent object lesson in the value of a backup, I suggest you spend the money on a new, separate external drive for Time Machine. You're going to want to backup the contents of the current external drive as well as the internal drive - while partitioning the external drive would allow you to add that data partition to the backup... how much space will you have left on the external when the dust settles?

Good point. Thanks for the help