migration assistant very slow

Hello

I had the same problem on Friday. I wanted to migrate (by Apple the migration assistant app) all my data (settings, apps, users) with about 420GB from my old MacBook pro 15" (2013) to a new MacBook Pro i9 over a Thunderbolt 2-3 connection. I put my old MacBook pro in the Thunderbolt target disk mode and started the migration. Transfer rate was in between the range of min. 2MB/s to max. 115MB/s, but mostly by 11MB/s. The whole migration process took 14 hours! This is equivalent to an average of 8.3MB/s and this not only disappointing but also ridiculous!

In the middle of the migration process I called the Apple Support and it became clear, that the Apple supporting team was not aware of this poor performance. The supporter had to search several times to find a single internal knowledge record, saying that poor performance is quite possible with the target disk mode, but without stating the reason for it. So the supporter and me argued about the technical reasons for it and found, that in the target disk mode the internal storage device is not connected directly by a high performance controller to the Thunderbolt interface but by a basic system controller. Thus our assumption was, that the performance should be much better, when the migration assistant is started within a full running MacOSX system.

As the same day I had to migrate other system, so I chose directly this approach (starting the MacOS migration assistant app on both sides with full running MacOSX). With this approach the migration assistant between a MacBook Air (2015) and an actual MacBook Pro 13.3 i7 performed about 65-80MB/s, mostly by 75MB/s with 200GB of transferred data (settings, apps, users). It is also to say during the migration process the fans of the MacBooks Air where at their max speed. So it seems that this approach is the best choice to migrate data with the MacOS migration assistant app over Thunderbolt. Please find in the following some hints to proceed:

1. start both system up (source and target).
2. connect both systems with a Thunderbolt (2-3 or 3-3 or 2-2) connection.
3. create on both system a "dedicated" network environment setting by choosing the Thunderbolt bridge as single network medium. Choose for the IP addresses the manual mode and enter some internal IP-address network range e.g. 10.90.0.10 for one side, on the other side 10.90.0.11 and as router 10.90.0.1.
4. disable all other network devices like Wifi and Ethernet to prevent the migration assistant will select perhaps the Wifi network device as connection base.
5. start on both system the migration assistant app and let search it the source system. The migration assistant should show the Thunderbolt icon in the progress display
6. start the migration process by selecting the appropriate data you want to migrate/transfer

best regards

I just wanted to follow up with this, as I mis-spoke before. I've now been able to run migration assistant while both machines are running (not in Target Disk Mode), using a Thunderbolt 3 cable, and it's very fast. When using Thunderbolt, migration assistant should show "Connection: Thunderbolt" once you start the transfer (once it starts the "Scanning files and folders" stage).

Note that you need an actual Thunderbolt 3 cable that supports fast data speeds - the charging cables that come with MacBooks do NOT. The Apple Thunderbolt 3 cables have thunderbolt logos on both ends.

Running Migration Assistant with the source machine in Target Disk Mode is still much, much slower in my experience.

20-80 MB/s is typical for these transfers because it's not a simple streaming transfer, the software is examining every file and figuring out whether it gets transferred and where to put it. Also, some of the operating system has a huge number of very small files which have considerable overhead to. move across. When you got only 3-4 MB/s that is indeed slow, but again the computer may be working to resolve differences between operating systems, when it's that slow it's working on things other than the physical transfer itself. it's all to make the transition be as smooth as possible when it completes.

The estimated time remaining provided is very rough and goes up and down as the process continues. It doesn't know exactly what is left to be done, only roughly, so its projections about time left to complete can be far off. I just did an operating system update on my laptop and it predicted it would take 20 minutes when it actually only took 2 minutes ...

I recently migrated over thunderbolt connection, 300 GB from old computer (MacBook Air) to new computer (MacBook Pro). It took about 6 hours, which is about 1 GB/min -- your transfer was about 2 GB/min. So yours was certainly faster than mine. I have also done several other migrations with older MacBook Airs over USB, always achieving somewhere between 1 and 4 GB/min. Your experience is in the middle of the range I have seen.

I've always felt that doing this migration using a TB2 cable to be slow and I've opted to just do a wired ethernet transfer which I've seen transfer over 140MB/s. I don't have to disable wireless as it detects an ethernet connection.

Yeah, no. That‘s shrugging off a terrible piece of software as normal. The mere act of copying shouldn‘t take more than 20min (apple claims a read speed of 2.2GB/s for the 2016 model - 1.25TB / 2.2GB/s = 9min 50s - so 20min is giving a lot of room). and „ensuring it ends up in the right place“ - that should fit easily in the time taken for the transfer of the data. 20min is a ridiculous amount of time for a modern CPU. Clearly Migration Assistant needs an overhaul.

I just wanted to pitch in with my experience. I manage about 40 macs in a corporate environment and have done a lot of migrations.

Over the past year or so I moved ~20 employees from MacBook Airs (2013-2014 models) to new MacBook Pro Retinas (non-touchbar version). These were all done using a thunderbolt2->thunderbolt3 adapter, and Migration Assistant was ran with both machines "live" (not in Target Disk Mode). I don't have MB/sec stats, but on average I considered these migration to be very quick - about 15-20 minutes (all machines have 128GB drives).

Now, I've recently had the need to migrate a few new MacBook Pros to identical machines. I've tried different USB-C cables, including the official Apple Thunderbolt 3 cable. I don't seem to be given the option to use Thunderbolt when trying to run Migration Assistant on both machines ("live"), so I've tried Target Disk Mode, and it seems dreadfully slow in comparison (2-3 hours, again with 128GB drives).

I'm assuming this difference is due to using Target Disk Mode, rather than a problem with the Thunderbolt connection, but I can't confirm that just yet. I'll be interested to try @relume's suggestion above to create a Thunderbolt network instead of using TDM.

Considering the amount of data that needs to be transferred, I'd say 9 hours is not unusual.

The limiting factor is not the Thunderbolt connection; it's all the "overhead" associated with MA making sure all the information is transferred to all the right places.

I am in the process of migrating 240GB of data from a 2014 Macbook Pro to a 2015 Macbook pro via thunderbolt

2 cable.

It has been 40 Minutes and I have only transferred 10GB.....

What is this epic failure?

This is embarrassing.

I now tried using carbon copy cloner and it is equally as slow....

I have been able clone a 40GB file with OSX and apps in less than 5 minutes in the past....

So why is a Migration so much different?

My fans are blazing,My machines are getting hot.

THIS ***** APPLE.

update: transfer-speed dropped to 3 a 4 Mb/s !

exactly my experience: extremely slooooooowwwww ... and moreover: the move was incomplete !!!

I am missing my entire "box" of old EUDORA mails, which I had "moved/converted" from my lab-PC to my first MacBookPro 15"(in 2013) - with Aid4mail and some help from the tech-support there - txs again -

in december 2018 I moved from that MBP15" to my new iMac27"Pro ...

after a lot of doing & fiddling (and many many hours) it worked for "the larger part" as proven by the fact that I am now typing this reply on a space-grey wireless full-sized keyboard and looking at the screen of that same space-grey big mac !

... except for my EUDORA mailboxes, which I still have to address on my old MBP15" !

Thanks for the info.

my today experience using MA to move from MBP15” (early 2013) to iMac27 Pro 2018 (delivered 3 days ago):

about 6 hours and 3 attempts becuase of different kind of interruptions

/* both upgradend to last vs Mojave

/* somewhat less than 1 Tb to transfer

/* using (my best) Ethernet cable with adapter to Thunderbolt on old MBP

/* MA running on both as instructed

frustrating:

/* both show the same duration estimate which fluctutates in both directions

/* only iMac reveiver shows speed, which varied from ~20 to ~80 MB/sec

/* time estimates varies both up & down apparently not directly related to speed

/* I note “jump” just now: from 2 hrs 36 min down to 1hr 11 min “ while I was watching”!!!

frustrating ....

mfg

fred