Transfer from external drive to new iMac complete

I’ve transferred from my late 2015 iMac to my new iMac successfully via external drive. I now want to backup new iMac with same drive. Should I erase and reformat before doing a complete backup of Time Machine from my new iMac?

iMac 24″, macOS 15.6

Posted on Nov 10, 2025 3:42 AM

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2 replies

Nov 10, 2025 7:40 PM in response to Dee from Basildon

Now that depends on several factors:


 So if you’d like to answer the following then I can hopefully give you some advice:


1.   Is the external drive a TM backup or a single clone?


2.   If the external drive is TM backup with history do you want to keep? (I would)


3.   What is the size of the external and how much free space still remains on it.


4.   What’s the size of the hard drive on the new iMac?

Transfer from external drive to new iMac complete

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