Clone one mac to another? I have 2 macbook pro A and B. I want to transfer A to B to make them identical. I have done something similar before by creating a disk image and then retoring a new hd from the same disk image. However, I tired the following and it seems I am missing something:


plug-in external HD with a newly created disk image from computer A into computer B
Launch disk utility on computer B
Click restore on the 1 and only partition 
Select the source to be the image on the external hd (.dmg file)
select the destination to be the partition.


Then I get a promted to scan the disk image but it fails with error unable to scan Resource Busy.

What am I doing wrong? Am I supposed to boot in recovery mode before?
Yes - booting to Recovery HD is the best option. Then you can do the bit for bit copy. I'm liking to do installs and then run Migration Assistant (over the network if needed or) by connecting over target disk mode to migrate from the old Mac to the clean new OS during the initial setup.

The procedure for that is to boot the new Mac to Recovery HD and to erase it completely if it already ran the setup assistant and created an initial user.


https://support.apple.com/en-us/HT204904


The reasons I like migration is:


You know the new OS is clean/pristine
It's faster - sometimes far faster
System unique files are actually unique so that the two "clones" aren't too close a match for some oddball edge cases and Time Machine backup cases.