Migrating From One Old Mac To Another with Factory Reset & OS X Yosemite



I had a need this past weekend to migrate from one old Mac running OS X Yosemite to another old Mac, also running OS X Yosemite. Apple’s Migration Assistant can get this done, but I was looking to zero out the target Mac first. You can google a few different ways to do this, but I thought I’d share my high level steps and observations here, since I know a lot of you that follow this blog are Macheads. Note that this is not a detailed step-by-step. Rather, this is the process I followed. You can google the how-tos for each individual step to fill in the gaps.

My goal was to start completely from scratch with a clean Mac running Yosemite that I would then use Migration Assistant to migrate to. I did not want to migrate to a Mac that had been running for a while and had a cluttered file system. To get that old Mac to a like new, factory reset condition, here’s what I ended up doing.

  1. Build a bootable USB OS X installer. I recommend a USB3 stick if you’ve got a Mac that supports it. The speed makes a difference.
  2. Back up the target Mac’s hard drive. Time Machine works fine. File copy can be a bit troublesome due to file permissions. The point is to make sure you’ve got everything off of the target Mac that you might want, because you’re about to blow it all away.
  3. With the OS X installer USB stick inserted, start up the target Mac in recovery mode (reboot, then hold down command-R until the Apple symbol shows) and then use the menu to erase the Macintosh HD. This won’t take long – just a few seconds.
  4. Once back at the menu, install OS X from the USB stick. This will take a while, and is where the USB3 speed helps move things along.
  5. After rebooting with the fresh OS X install, you can use the Migration Assistant tool to copy applications, user profiles, and data from the old Mac to your fresh new Mac.
  6. Migration Assistant over the network will take a while. I was going between Macbook Pros over wi-fi, the slowest way possible, really. If you figure both the source and target Mac are going through the same AP, then the effective speed of the AP is cut in half since only one client at a time can be on the air, right? Full-duplex Ethernet would be a lot faster if you have that option.I moved roughly 80GB of data between systems. On an Apple Airport Extreme AP where both 802.11n MBP clients were in the same room as the AP and claimed to have 450Mbps of available throughput, the migration time was about 2 hours.
  7. I had to be careful since I was moving from a machine with 256GB of storage to one with only 128GB of storage. I could not migrate all the things, choosing to dump some data onto my Synology array instead. Something to think about if you’re migrating between Macs with mismatched storage.

After The Migration

I found that the applications on the target Mac mostly just worked, but a few had licensing issues or other issues. For instance, I had to re-apply the license key to the Clean My Mac application. On the other hand, Rogue Amoeba’s Audio Hijack license migrated okay. Somewhere in the middle is my older version of Adobe Audition CS6, that claims the application is damaged and needs to be reinstalled, even though it seems to work completely fine after acknowledging the “you should really reinstall” message.


Other than that, it’s hard to tell that I moved from one machine to another. I use Spaces (multi desktops), and they are exactly the same. The customized external monitor color profile is correct; the monitor looks bad without that, so I would have noticed if it had not been migrated. Screensaver and backgrounds the same. iCloud keychain import was a bit of a thing to authorize, but no big deal. Dropbox needed me to re-authenticate, as did Google Drive. Wireless SSIDs and keys were migrated successfully. Bluetooth was a little dodgy, now that I think about it. At first, the target Mac seemed to know about two Bluetooth devices I’d paired on the old system, but I ended up having to re-pair them both (a Magic Track Pad and stereo headphones).

Overall, no complaints. Pretty happy for it to have been as easy as it was.

About the author

Ethan Banks

Most people know me because I write & podcast about IT on the Packet Pushers network. I also co-authored "Computer Networks Problems & Solutions" with Russ White.

Find out more on my about page.


Most people know me because I write & podcast about IT on the Packet Pushers network. I also co-authored "Computer Networks Problems & Solutions" with Russ White.

Find out more on my about page.

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