Using an external startup disk to replace the internal one?

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Level 1

8 points

Using an external startup disk to replace the internal one?

Hello everyone,

I have a Late 2009 iMac 27" running OS X Mavericks that I wish to upgrade.

More specifically, I want to replace the internal HDD with an SSD, for this I've already got all the necessary tools including the hard disk sensor cable, 2.5" to 3.5" disk adapter, the SSD itself, ...

My plan to do the upgrade is:

Connect the SSD via an USB adapter
Install macOS Sierra to the SSD as an external startup disk.
Boot the iMac from the SSD over USB.
Use Migration Assistant to copy over my data from the internal HDD to the externally booted SSD.
Disassemble the iMac & replace the internal HDD by the SSD as described by OWC.
Done?

I'm not directly starting with the operation as I'm not sure of these things:

Step 4: Will Migration Assistant accept the mounted internal disk filesystem as a source? This is not documented in the support page. This post suggests it does.
Step 6: Can I use a (previously) external startup disk (the SSD) to replace the internal one without any changes to some bootloader? Is this "plug-n-play"?

I could just make a bootable USB stick installer, replace the HDD, do a clean install on the SSD. But then I'd need either a redundant backup of the internal HDD or a 3.5" HDD USB adapter to move the data.

Do you think this procedure would work? Thanks in advance!

iMac, OS X Mavericks (10.9.5)

Posted on Jan 9, 2017 12:41 PM

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Answer 1

Best reply

BDAqua

Level 10

238,997 points

Jan 10, 2017 1:30 AM in response to Gazibar

It should work, haven't done Sierra but previous OSX versions allowed Migrating from internal drive.

PS. On first boot of the external Install you should use Setup Assistant rather than signing in then using Migration Assistant.

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Answer 2

babowa

Level 9

78,097 points

Jan 9, 2017 7:53 PM in response to Gazibar

A little quicker way would be:

install SSD in an enclosure, plug it in, format it Mac OS Extended (Journaled) and GUID partition scheme

Install cloning app on the internal

Clone your current internal system to the SSD with CarbonCopyCloner or SuperDuper.

Test to make sure it boots.

Eject SSD and, if you wish, go ahead installing it.

Boot up with your new SSD.

Nothing else to do since you have your complete system on it already.

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Answer 3

Jan 11, 2017 4:13 AM in response to Gazibar

If you really want a "clean start", I would back up all data to another drive

(Which you should be doing anyway. Trusting your digital life to a single device

is a disaster waiting to happen).

Then, do the "clean" OS install to the new drive externally. I would then test

it to insure all went well.

Next, do a fresh install of all your applications. Again test.

Then move your data. And yes, test yet again.

Using Migration Assistant after a clean install can likely bring all that

"bloat" over to the new system, which is why I suggest the above if you

really want a "clean" system.

As for all the testing, better to do it outside since the drive is such a

pain to install internally.

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Answer 4

Gazibar Author

Level 1

8 points

Jan 11, 2017 4:25 AM in response to woodmeister50

Hi, this is exactly what I did yesterday.

Progress so far: installing macOS Sierra to the external drive worked perfectly, starting up from it too.

Though the Migration Assistant "worked" with the internal drive as a source, I figured out, like you say, that it has very limited selection capabilities (so it would indeed carry over the bloat).

I manually moved my data & important settings. The only problem was moving the mails from Mavericks to Sierra. It was not possible to do manually, Apple changed the structure of the app. You have to start from scratch creating accounts, importing mailboxes & moving mails...

Everything seems to work fine externally, the only uncertainty now is whether the Sierra disk will boot internally as well...

Thanks!

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