I ran a transfer of about 4 TB of files from my failing Mac to my new Mac. After 62 hours of direct connection transfer time (which seems inexplicable), I was told at the very end of the process that not all files could be transferred without telling me which ones I may have still stuck on my old Mac.

Is there anyway I can get a list of the failed transfer files or do I have to start the entire process over and hope it doesn't fail a 2nd time over the 3 day span of time?

2 Answers 2


You can compare contents by setting the source computer to Target Disk Mode, connecting both computers via cable or network, and compare contents using a tool like Beyond Compare (long free trial, more than enough for this job).

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    I just ended up copying everything to an external drive then replacing everything on the target Mac, but this would have been a good option as well. Completely forgot Beyond Compare can be used for more than just code merges. :) May 12, 2021 at 18:31

Open a terminal and execute:

diff -qr /Volumes/newharddrive /Volumes/oldharddrive

you have to change the names of the hard drives (or directories) according to your setup.

diff -qr /Volumes/newharddrive /Volumes/oldhardrive | grep ' differ'

is a variant to reduce the output clutter.

You can redirect the output from the terminal to a text file for easier reading:

diff -qr /Volumes/newharddrive /Volumes/oldhardrive >compare.txt

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