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Migration Assistant - which data transfer method is faster?

P

pward

macrumors regular
Original poster
Nov 26, 2008
138
48
Hi,

I set up my brand new 5K iMac yesterday and used Migration Assistant to restore the Time Machine backup from my previous iMac, a 27" Mid-2010 model. Migrating c.450GB of data took six hours.

I will be passing on my old iMac to a friend who will need to restore data from their old iMac. They have a Time Machine backup which we could use but would the migration process be quicker if we connected both iMacs together with an Ethernet cable?
 
How is the external drive connected to the iMac?

I'm guessing USB, and as such, I think that USB would be faster then gigabit ethernet, and so it would actually be slower using ethernet, then USB.

I too found TM to be slow, I would recommend using Carbon Copy Cloner to back up the iMac to an external drive and then use that to restore to the new iMac.

I've gone the CCC route and it only takes a fraction of time that TM needs.
 
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Yep, external drive was connected using USB but it was USB 2.0 as that was all my Mid-2010 iMac would support.

Would USB 2.0 really be faster than Gigabit Ethernet?

Thanks for the tip on Carbon Copy Cloner.
 
pward said:
Yep, external drive was connected using USB but it was USB 2.0 as that was all my Mid-2010 iMac would support.

Would USB 2.0 really be faster than Gigabit Ethernet?

Thanks for the tip on Carbon Copy Cloner.
Click to expand...

USB 2.0 is definitely not faster than GigE and honestly USB 3.0 with its overhead likely wouldn't be either. You're going to be limited by the transfer rates of the drives involved either way, but since you're lacking in USB 3 on both machines, definitely go Ethernet. Even with SSDs (except for the very newest Macs with PCI-E speeds), your bandwidth over Gigabit Ethernet will far outstrip the ability of the drives to read/write data.
 
torquer said:
USB 2.0 is definitely not faster than GigE and honestly USB 3.0 with its overhead likely wouldn't be either. You're going to be limited by the transfer rates of the drives involved either way, but since you're lacking in USB 3 on both machines, definitely go Ethernet. Even with SSDs (except for the very newest Macs with PCI-E speeds), your bandwidth over Gigabit Ethernet will far outstrip the ability of the drives to read/write data.
Click to expand...
Gigabit ethernet really isn't all that fast, as the data transfer rate is only 125MB/s theoretical maximum.

In real life you may only see 60% - 80% of that speed on a typical home network. At those transfer rates it won't "far outstrip" the R/W data rates of modern disk drive systems or even individual drives, let alone SSDs. USB 3.0 or Thunderbolt would likely provide better data transfer rates if available on both devices.
 
torquer said:
USB 2.0 is definitely not faster than GigE
Click to expand...
I found in my real world usage, that it was. I'd have a NAS connected via ethernet to my Mac, and an external drive to the USB 2.0 port on my MBP. The USB would copy the data faster then it would go over the wire to the NAS
 
Im waiting on my 27in to arrive. My 12 MBP has only 10gig free of the 512 ssd (went with 1tb ssd for new iMac) My photos take a HUGE amount of it. I kind of want to do a clean start but want things like apps, docs, etc on the new one. Is there a preference selection where it doesn't take 340 gig worth of photos to the new one? Whats so special about Carbon copy? Thanks for any input
 
terrymaz said:
Is there a preference selection where it doesn't take 340 gig worth of photos to the new one?
Click to expand...

Yes... if your Photos library is in the default Pictures folder, when you get to this step in the migration, just click the triangle next to your user name and scroll down and uncheck Pictures and that folder will not be migrated.

iur.png
 
To find which kind of way is faster, you should know what happens when the migration is doing.

For Time Machine to Mac, the files transfer from the backup disk to OS X disk, as the Time Machine contains all the history files, some of the files in the latest backup is marked by links to the old backups. So comparing to direct link between Macs. Time Machine need extra time for this.

Also, most of the backup files are some files, when read those files, hard drive needs to locate each of them separately. Since the files are very small, comparing to the transfer time, the finding time becomes big. Especially if you transfer them by network, the latency is even bigger.

Conclusion:
1 If both side are SSDs, it is the best
2 Use directly connect if you care the time length most

I also suggest erase and reinstall the OS X before he does the migration.
 
Weaselboy said:
Yes... if your Photos library is in the default Pictures folder, when you get to this step in the migration, just click the triangle next to your user name and scroll down and uncheck Pictures and that folder will not be migrated.

View attachment 608185
Click to expand...


Thanks. I'll have to check. On my MBP everything was being imported directly to Aperture for pics. Im making the switch to Lightroom and photoshop for the iMac though since Apple is no longer supporting Aperture. Grrrr
 
hfg said:
Gigabit ethernet really isn't all that fast, as the data transfer rate is only 125MB/s theoretical maximum.

In real life you may only see 60% - 80% of that speed on a typical home network. At those transfer rates it won't "far outstrip" the R/W data rates of modern disk drive systems or even individual drives, let alone SSDs. USB 3.0 or Thunderbolt would likely provide better data transfer rates if available on both devices.
Click to expand...

The OP stated he was transferring from a 2010 iMac which is limited to either SATA1 or SATA2. Unless they manually upgraded to an SSD (possible but not mentioned), we're dealing with a 5400 RPM disk drive most likely with a transfer rate of around 40-50MB/sec. So yes, gigabit would far outstrip that disk transfer rate. Also as a 2010 iMac USB 3.0 isn't available making that not an option. I probably spoke less than artfully because I included the context of the OP's comments.

Where USB 3.0 is available on both devices and both devices are SSDs on SATA2 or better, it is preferable. Thats not the case here based on the OP's statements though.
 
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