Fastest way to transfer from old iMac to new iMac

[SallyGB]

When the hard drive in my old iMac with 2 TB fusion drive started acting up, I replaced the HD with an OWC 1TB SSD drive. When that new drive very quickly started operating very slowly (confirmed by terrible benchmark testing, eg. read/write of 77/4 mb/s ), I replaced it with another one that quickly developed the same problem. I don't know if it's the computer or the SSD's, but I've had it and have a new iMac (fully loaded and with 1TB SSD) arriving this Wed. Because of all the issues I had been having, when I installed the first replacement SSD, I reinstalled everything, so there's no old junk. I am running Mojave and assume the new iMac will be Mojave as well, but will upgrade before file transfers if it is not.

I would appreciate recommendations for the fastest way possible to transfer my data and apps from the old to the new iMac. I've considered:
#1--Copy data from the sluggish new SSD to the smaller old iMac's SSD (since it is significantly faster) and then connecting the old/new iMacs with Thunderbolt 2/Thunderbolt 3 cable and using Migration Assistant. I would have to first offload all my Windows 10/Parallels files on that faster SSD to an external drive.
#2--Same as above, except copy data via a TimeMachine backup
#3--I have a Time Machine backup on a 500 GB Samsung 970 NVMe PCIE M.S SSD housed in an external case with a USB-C connector (backed up with a USB-C to USB 3 cable).
Any other faster/better way to do this? There are roughly 110 GB's on the slow SSD if I don't double that by backing up my Dropbox files.
Thanks!

 

[mreg376]

I found that the best, and most convenient way is to use Migration Assistant on both machines with both machines connected to your network by ethernet. Wifi will work too, but likely slower.

 

[SallyGB]

I found that the best, and most convenient way is to use Migration Assistant on both machines with both machines connected to your network by ethernet. Wifi will work too, but likely slower.

Wouldn't it be faster if I used a Thunderbolt 2 to TB 3 connection?

 

[mreg376]

Possibly. But you'd just have to make sure that Migration Assistant supports that type of connection.

 

[Fishrrman]

If you follow my instructions, I guarantee a 98% success rate or better.

1. You need an external drive, USB3, USB2, thunderbolt, anything.
2. You need CarbonCopyCloner or SuperDuper (both are FREE to download and use for 30 days) -- going this way "costs you nothing".
3. When the new iMac comes, take it out of the box and set it up, but DON'T press the power on button
4. On the OLD iMac, do a CCC (or SD) "full clone" of the internal drive. This will be a record of the internal drive "exactly as it was" at the moment you "moved up" to the new iMac.
5. When done, power down the old iMac, disconnect the drive and connect it to the NEW iMac.
6. Press the power-on button. Begin setup.
7. When setup assistant asks if you wish to migrate from another Mac or drive, YES, you want to do this, so....
8. "Aim" setup assistant at the external cloned backup and give it a few moments to "digest everything".
9. Setup assistant will present you with a list of stuff to migrate (apps, accounts, settings, data).
10. Select those items you wish to bring over and "let 'er go". It will take a few minutes.
11. When done, you should be presented with a login screen (and a desktop) that looks just like it did on the old iMac.
12. Done.

 

[Shivetya]

I found that the best, and most convenient way is to use Migration Assistant on both machines with both machines connected to your network by ethernet. Wifi will work too, but likely slower.

I used wifi to start it on my last migration as direct connect would not work at start, as soon as it showed progress I just cabled the two machines together and it went quite quickly.

 

[xgman]

If you follow my instructions, I guarantee a 98% success rate or better.

1. You need an external drive, USB3, USB2, thunderbolt, anything.
2. You need CarbonCopyCloner or SuperDuper (both are FREE to download and use for 30 days)
3. When the new iMac comes, take it out of the box and set it up, but DON'T press the power on button
4. On the OLD iMac, do a CCC (or SD) "full clone" of the internal drive. This will be a record of the internal drive "exactly as it was" at the moment you "moved up" to the new iMac.
5. When done, power down the old iMac, disconnect the drive and connect it to the NEW iMac.
6. Press the power-on button. Begin setup.
7. When setup assistant asks if you wish to migrate from another Mac or drive, YES, you want to do this, so....
8. "Aim" setup assistant at the external cloned backup and give it a few moments to "digest everything".
9. Setup assistant will present you with a list of stuff to migrate (apps, accounts, settings, data).
10. Select those items you wish to bring over and "let 'er go". It will take a few minutes.
11. When done, you should be presented with a login screen (and a desktop) that looks just like it did on the old iMac.
12. Done.

How is this different than doing the same with a fresh full TM backup? Are there more cache files copied over via the clone setup method?

 

[theluggage]

Wouldn't it be faster if I used a Thunderbolt 2 to TB 3 connection?

Possibly, but you’d need a $50 TB 2 to 3 adapter plus at least one TB cable, and you’re probably only going to do this once - just leave it chugging away overnight.

On the “slow” SSD - how full is it (considering you went from 2TB to 1TB)? A full-to-bursting SSD is likely to get very inefficient (and it’s usually beneficial to leave some space unallocated - I.e. make the partition 10% smaller than the free space, although some SSDs may have that baked in - for example, I wouldn’t mess with your new iMac).

 

[smirking]

If you follow my instructions, I guarantee a 98% success rate or better.

Damnit! I wish I saw this message sooner. I'm in the middle of my second attempt to migrate to a new MBP after my first Mac to Mac transfer ended up leaving behind 80% of my files and 100% of my settings. I used a TB3 cable between the Macs. It finished a 1.5TB migration in about 4.5 hours. Even though the files didn't transfer, I assume it still processed as if it were transferring so I'd guess that 4-5 hours for a 1.5TB migration would hold true.

I'm currently on plan B. I have an ethernet line to my Time Capsule. I'm about 12 hours in with 5 left to go. If this migration also doesn't work, I'll give this a try.

 

[smirking]

Ok, I had a hell of a time getting all of my files from a 2016 MBP to a 2018 MBP. I did the migration three different ways and four times in total. I did it all those times because my migation kept failing. The fourth time was the charm.

1) MBP to MBP using Target Disk Mode
2) From Time Machine Backups over Ethernet
3) Using @Fishrrman's method from a clone of my drive done with SuperDuper

The reason why my migration kept failing actually had nothing to do with the way I migrated it. A permissions issue was causing most of my files to be unreadable during migration, but in performing the migration so many different ways I learned a few things.

• OMG, if you have more than 512GB of don't restore from Time Machine over Ethernet. It took me 24 hours. It failed too and it's possible that absent the errors, the migration would have finished sooner, but it still would have taken a long time.
• MBP to MBP with a TB3 cable was hands down the fastest way to do it, but has the drawback of tying up both of your machines. This method took about 7 hours to (not) move 1.5TB.
• I'm not sure if Fishrrman's method of migrating from a cloned copy of your old drive is any more reliable than any of the other methods, but it's definitely more convenient and probably faster than restoring from Time Machine. It took me 12 hours to restore 1.5TB from a cloned drive through a USB3 cable.