Migration Assistant is the easiest way to transplant the heart
and soul of one Mac to another. While it used to be fragile and
frequently failed or required multiple attempts, I've found it
increasingly reliable in recent years. I've used it a few times in
the last few months, and it worked with near perfection.
Migration Assistant has improved on the number of ways it lets
you connect two Macs, and has become better at using the fastest
method of connection. On newer Macs, the best way will always be
Thunderbolt-to-Thunderbolt. This requires a Thunderbolt data cable.
For somewhat worse but not terrible performance, you can instead
use a USB 3.1 or 3.2 cable with USB Type-A or USB-C on both ends.
(See this guide to determining what kind of
USB-C-tipped cable you have if you're not sure.)
If you have an ethernet port on both devices, you can connect a
standard ethernet cable, but that will only deliver 1Gbps compared
to the potential 10 to 40Gbps of USB 3.1 or Thunderbolt 3.
After going through the
initial steps on each Mac of launching Migration Assistant and
validating one Mac to the other and beginning the transfer,
Migration Assistant displays the network chosen on the machine
that's copying as Current connection near the bottom of the
If that's not the method you prefer, or you want more
information, you can click the Connection Details link at the
lower-right corner. This brings up a dialog that shows the
performance of all available methods. In the figure, I was
migrating my wife's data from one laptop to another; Thunderbolt 3
correctly kicked in using a Thunderbolt 3 to Thunderbolt 3
recognized three possible connection methods and picked the best by
far: Thunderbolt to Thunderbolt.
Migration Assistant's reported speed of 192MBps (1.5 Gbps) not
only seemed phenomenal, but the transfer of hundreds of gigabytes
took about 30 minutes.
macOS reported the other two available methods as poor, showing
a yellow dot to their right instead of a green one, as next to the
Thunderbolt entry at the top. A peer-to-peer network, which engages
a special direct Wi-Fi mode between the two Macs, would have been
over ten times slower. That was fabulous compared to the very low
data rate of 1MBps (8 Mbps) reported over Wi-Fi, likely because one
or both machines were connected to a distant Wi-Fi gateway instead
of the one just a few feet away.
If you don't like method chosen, you can cancel the migration
and test cables, change the Wi-Fi network in the setup stage, or
purchase a new cable to speed things up.
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