Wednesday, July 13, 2022

Migration Assistant Magic

Nick Heer:

You agree, it opens Migration Assistant on your new Mac — you open it manually on your old one — and then it runs a few tests in the background to automatically select the fastest transfer method.

In my case, this was peer-to-peer at a painfully slow three-to-six megabytes per second. To move the half-million files from my old Mac, it was looking like a twelve hour operation. But I remembered I had a first-generation Thunderbolt cable laying around and an adaptor — and the tip Siracusa relayed in that podcast episode: Migration Assistant will automatically switch to the fastest method available, even partway through a migration.

Peer-to-peer is faster than regular Wi-Fi, and it always seems to be at least twice as fast as the original estimate that it gives. I recently migrated my server from an old MacBook Air to an M1 Mac mini, and I didn’t have an adapter for the old Thunderbolt port. So it took a while, but the most important thing is that it did the job properly and unattended.

Thunderbolt is much faster but not as much faster as I expected.

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I always forget that Migration Assistant is a server as well as a client. Recently I've only been using it to grab Time Machine backups and Target Disk Mode disks on Intel Macs, but of course you can also transfer from a running system. It's a wonder they don't just use the SMB support or something. Lots of work, just to migrate data, but I'll give it another try to upgrade my own Mac Mini server soon.

Dimitri Bouniol

I’d love to know *why* thunderbolt is limited to 10Gbps for networking, when it has much more headroom available… Even if you account for the mandatory display port bandwidth, wouldn’t we at least be able to support 20 or even 30Gbps duplex?

Although it's true host-to-host Thunderbolt is (surprisingly) limited to 10 Gbps, it still seems to me to be more reliable than 10 Gb Ethernet.

Has anyone tried using Recovery to restore a Time Machine backup onto a new Mac? Is that allowed as a means of migrating?

@Sebby Yes, I have done that, and it works fine.

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