Finally...got it working.
TLDR; I put the destination machine in target-disk mode, connected it with USB-C 3.1 Male-to-Male cable and used Carbon Copy Cloner to create a new sparsebundle on the root of the drive, than ran migration assistant after mounting it while running a dummy account.
It is worth noting I wanted to do a few things:
- Copy my machine as completely as possible (IE all my bash-profiles (I am a developer), and installed frameworks)
- Have access to the source machine during the day for work! I don't think this is too much to ask in 2018 for a transfer of 500Gb to run over a LAN or USB-C 3.1 with all modern equipment)
There are A LOT of worthless "Migration Assistant" explanations out there. So I figured I'd post a few details of what I learned this week. This is my experience it may/probably won't work for everyone else. Plus I had the advantage of migrating 500Gb to 1TB which in the end was my saving grace.
Paths I tried:
- Open Migration Assistant on both machines both connected to the same router (late model Linksys AC9000) network over CAT5 cables
Result: Migration assistant runs, and transfers to new machine in 2-3 hours. However (same as initial question lots of "Unable to transfer file" errors, when logging in, no Docs, Applications in directories, etc., keychain warning). FAIL
- Run Time Machine backup from source machine to external NAS (both connected over CAT5 to same Linksys AC9000 router). NAS is 12TB Symbology
Result: Time Machine taking forever after 3-4 days I attempt to use
lowpri_throttle_enabled hack, backups run faster, but keeps looping on "Backing Up" (Both Migration Assistant and Time Machine have USELESS "progress indication" FAIL - Gave up after backing up for 2-days
- Go to Apple Store, and as employee: "What does Apple use to migrate machines when customers ask it to be done for them?" Answer: "USB-C, it costs $99, and there is no timeframe, you leave us both computers and we call you when it's done."
Buy generic Microcenter Inland brand "Super Speed USB 3.1 10 Gbps" USB-C Male to USB-C Male (Apple Store DOES NOT STOCK a USB-C 3.1 Male-to-Male cable as of this posting)
Connect machines with cable, and put source in 'Target Disk Mode' (Hold "T" key while booting), open 'Migration Assistant' on destination machine.
Result: Migration Assistant relatively quickly manages to collect source-information calculations (User Account, Application, Network Settings, etc. and sizes for each - though this does not seem to have much practical effect it takes A LONG TIME) Start migration, Migration assistant shows "Starting Up" for 3-hours, no change, or estimation or copy-speed indication. FAIL
- Download Carbon Copy Cloner, I was suspicious of 3rd party back-up tools being capable of working appropriately with Apple's convoluted back-up scheme and sparse-bundle file format, but CCC 5 is definitely an excellent tool, so shameless plug to them! There is also a free-trial so you don't have to pay to use it full-featured for 30-days, but you should buy a license and save yourself the brain-damage of dealing with Time Machine.
Result: Create new backup on NAS (Same Symbology 12TB NAS as before), since my Time Machine backup indefinitely never finished after 4-days. Wait (not as long as Time Machine) but overnight 4-5 hours over LAN CAT6 now. Open Migration Assistant on target machine, attach network drive, see my backup, and wait.
Migration assistant says: "Loading Backup" for 12-14 hours, I cannot click "Continue" as it is deactivated. I can see network traffic moving from the NAS to the computer and so on, but after 15 hours I give up. FAIL
- Put destination machine into target disk mode, and connect with USB-C 3.1 Male-to-Male cable to source. Format target drive, remember it has 1TB of space, and backup is only ~500Gb. Open Carbon Copy Cloner, and create new back-up on root of attached target-disk drive. This takes about 2-hours (relatively fast compared to other attempts). Attempt to boot into recovery (Discover machine just hangs at the Apple Spinning Globe screen, until I place backup sparsebundle inside of a directory on the root of the drive, I just call it
Result: I than reinstall MacOS, and create a dummy account (as suggested by @Zonker.in.Geneva) and than boot, run updates, verify that I still have my
.sparsebundle archive, than I "mount it" (Double click it in Finder), and than open Migration Assistant.
Now I see
Macbook-Pro-2017 as a source, I select it, and it very quickly manages to do the size calculations. I start the migration once they complete, it's worth noting that as a developer I have A LOT of tiny files (it calculated 3.5 million in the sparsebundle),
Migration takes ~12 hours. Again the time/progress indicators are WORTHLESS. Sometimes it says reading 130mb/s, sometimes nothing. Sometimes 3 days to finish, sometimes 3 hours. It's completely worthless.
Finally, I reboot the machine and it says "Migration Complete" and magically, I am able to login to my account as if I was on the original machine, and it appears so far that everything is as expected.
The big caveat here is that I had a 1TB machine as a destination for ~500Gb worth of files, and after migration I only have about 50Gb of space left before I delete the sparsebundle. SUCCESS, now if I could only get the last week of time I spent messing around with this back. Thanks for the productivity bump Apple. 🤯