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can't use target disk mode

timelessbeing

timelessbeing

macrumors 6502
Original poster
Oct 15, 2009
450
131
I've got a 2014 Retina Macbook Pro running Catalina 10.15.7

I entered TDM by holding 'T' on boot.

I get a floating Thunderbolt icon.

I connected it to my new 2019 16" MBP also with Catalina 10.15.7

I used a Superspeed USB-A<>USB-C 3.1 data cable (which says Apple compatible on the box)

I get a chime and 'plugged in' indicator, but no disk shows up.

Apple's own documentation says: "To connect a USB-C port to a USB-A port, use a USB-A to USB-C cable that supports USB 3.0 or USB 3.1, such as the Mophie USB-A Cable with USB-C Connector."

https://support.apple.com/en-us/HT201462

There is nothing in Disk Utility, and nothing on the USB bus in System Information either.

Both are APFS formatted. I am not using encryption


Why doesn't it work?
 
Floating Thunderbolt icon means it is expecting a Thunderbolt connection between the Macs. A Thunderbolt connection requires a Thunderbolt cable.

I don't think USB Target Disk Mode is an option on the 2014 Retina MacBook Pro. I think the options there are FireWire and Thunderbolt, same as my 2015 Retina MacBook Pro. A FireWire icon will appear next to the Thunderbolt icon only when a Thunderbolt to FireWire adapter is connected. When the TDM connection is made, the icon for type of connection used will remain while the other icon disappears. For example, a Thunderbolt connection will cause the FireWire icon to disappear.

For my Mac mini 2018, the options are Thunderbolt and USB.

If you try TDM on the MacBook Pro 2019, and hold T, then it might show the Thunderbolt and USB floating icons. Then you can connect it to another Mac like the MacBook Pro 2014 with USB or Thunderbolt. A Thunderbolt TDM disk cannot be connected to a PC - maybe a USB or FireWire TDM disk can be connected to a PC if the TDM disks are pretending to be standard FireWire or USB mass storage class devices.
 
How much stuff do you need to transfer?
Are you just "setting up the new one" for the very first time?

There are other -- quite easy -- ways to do this.
 
150ish GB. I'm aware that there are a few ways to skin this cat. I was just hoping to make it go faster with a $12 cable.

I'll probably just use wifi.
 
wifi will take forever.

Use an external USB drive (hard drive is fine, don't need SSD).
Use the finder to copy things from the OLD Mac to the drive.
Connect the drive to the NEW Mac, and let its icon mount on the desktop.
Then, click ONE time on the drive icon and bring up the "get info" box.
Go to the bottom of get info, click the lock, and enter your administrative password (the one that you're using on the NEW Mac).
Put a check into "ignore ownership on this volume".
Close get info.

You can now manually copy stuff over to the NEW Mac, and all the items you copy will "fall under the ownership" of your NEW account.
 
I will be using an external drive for all the bulky stuff, but I want to use migration assistant to transfer applications and settings since it's very time consuming.
 
"I want to use migration assistant to transfer applications and settings since it's very time consuming."

If you have already created a NEW user account on the NEW Mac, your old "settings" cannot be migrated from the OLD account to the NEW one using migration assistant.

That trick works ONLY when you are setting up the Mac "new for the very first time" (with no pre-existing account).

That's because even though you may have the same username and password, the Mac will think "it's somebody different" because it's coming from another Mac.

I can suggest a way that WILL WORK, but you must realize that once it's done, you'll need to DELETE the new user account on the NEW Mac.

Is the old Mac still set up and fully usable?
 
When I was going through the setup, it offered that I could run MA later. I don't mind turfing the user account that I created because I haven't done much with it yet.

The old Mac is usable.
 
I just successfully performed the data migration.

Fishrrman said:
If you have already created a NEW user account on the NEW Mac, your old "settings" cannot be migrated from the OLD account to the NEW one using migration assistant.
Click to expand...

Yes they can.

Fishrrman said:
That trick works ONLY when you are setting up the Mac "new for the very first time" (with no pre-existing account).
Click to expand...

Not true. I set the computer up, made a new account, and used it for three days. Today I ran the assistant

Fishrrman said:
you'll need to DELETE the new user account on the NEW Mac.
Click to expand...

MA simply asked me if I wanted to overwrite the existing account, which I did.
 
timelessbeing said:
I just successfully performed the data migration.

Yes they can.

Not true. I set the computer up, made a new account, and used it for three days. Today I ran the assistant

MA simply asked me if I wanted to overwrite the existing account, which I did.
Click to expand...
You can type the following commands in each system to make sure they have the same user id (which is usually 501 for the first user).
id joevt (use your own user id here)
echo $UID
 
"MA simply asked me if I wanted to overwrite the existing account, which I did"

OK, that's pretty much in line with what I wrote above, that using MA would bring over your "old" account, separate and apart from the new.

Instead of "leaving the new account" in place (for you to delete afterwards), it "over-wrote" it -- which, in essence REPLACES the exiting account with new data.

It's been a while since I used MA, I didn't realize that it would offer you the option to replace one account for another (if both accounts used the same username).
Apparently, it does.

Was anything you created (in your account) BEFORE you migrated still there after MA did the "over-writing" ??
I'm wondering if it did a complete "replacement"
or..
Perhaps a "merge" ??
 
OK I see. I misunderstood you.

I didn't dig very deeply. The computer name remained. Seems to be a complete replacement.
 
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