Reinstall OSX onto Fusion iMac 27" late 2013

[kirkster501]

Want to do an update to this machine, which is still a great computer for simpler tasks like browsing, remote desktop, word processing, teams etc.

Last night I booted off of a USB and I wanted to trash the entire file system and start again with a fresh install. However, couldn't seem to work out what I needed to do with the fusion drive.

Any advice or guides please? I want to do this as a dummy run ahead of opening it up and updating the HD to a SSD. Indeed, when I have done the SSD upgrade do I need to even bother with the fusion drive any more?

Thanks

 

[Juicy Box]

I am having trouble understanding your post, like, what you have done, what you want to do, etc.

However, couldn't seem to work out what I needed to do with the fusion drive.

What do you mean? How to install a fresh OS on the Fusion Drive? How to replace the Fusion Drive with something else? How to split the Fusion Drive?

Can you explain?

I want to do this as a dummy run ahead of opening it up and updating the HD to a SSD.

I read this a few time and I cannot understand what you me. Maybe it is an idiom?

Do you want to replace the internal HDD to a SSD? replace the internal SSD with another SSD? Both? Or just use a SSD instead of the Fusion Drive, externally?

Indeed, when I have done the SSD upgrade do I need to even bother with the fusion drive any more?

This all depends on what you want to do. You may have explained that already, but I just am not sure what you are intending to do.

If you are using an external solution, you can ignore the Fusion Drive.

You could also use it as a bootable back up, which is helpful for trouble shooting as well.

You could spit the Fusion Drive, and use the faster 128GB SSD part as a scratch drive and use the HDD for storage or a bootable back up.

You can just use it as storage.

There are a bunch of options for you, depending on what you want to do.

 

[MBAir2010]

i read this article from Macworld recently and this might or might not help since this is about speeding up which you might want to do without reason anything.

 

[Fishrrman]

You said you want to "trash the entire file system and start again with a fresh install".
If that's really what you want, read on.

First thing to do:
BACK UP THE EXISTING DRIVE.
(not much more to say about that)
I recommend CarbonCopyCloner, free to download and use for 30 days.

Next thing:
Boot from the USB flash drive.

Note: I've never owned a fusion drive. Things -might- work differently than the following. If I'm wrong, hopefully others will jump in to correct me.

After that:
Open disk utility.
Is there a "view" menu?
If there is, go to it and choose "show all devices" (important).
If there IS NOT a view menu, don't worry about this, go on to next step.

Next step:
Click on the line on the left that represents the "fused" drive. I'm not sure how this is presented to the user (in disk utility) on a fusion drive Mac. It might be "the top line", or it might not be.

Now, click the erase button.
You need to specify the file format you want (you didn't tell us which version of the OS you use, that's important information).
Since the fusion drive is created from two individual drives, I'm going to GUESS that you want to "erase" the "fused volume", rather than the two individual drives, without "destroying" the fusion that bonds them together. But again, that's just a guess on my part.

If it's High Sierra or earlier, I believe you want "Mac OS extended with journaling enabled, GUID partition format".
If it's Mojave or later, I think you want "APFS with GUID partition format".

Then, erase the drive.

When that's done:
Open the OS installer and start clicking through.
Be aware the Mac may restart one or more times, and the screen may "go black on you" and stay that way for a few minutes before proceeding.
Be patient.

When finished, you should see the initial start screen "Choose your language".
Begin clicking through.
At the appropriate moment, setup assistant will ask if you wish to migrate from another drive.
If you do, connect the backup and give setup assistant time to digest things.
Then choose what you wish to migrate and let setup assistant do its thing.
It will take a while, again... be patient.

When done, you should see your account login screen.

 

[kirkster501]

Hi guys, many thanks.
I want to reinstall OSX from scratch by reformatting the disk/disks and start again from clean OSX install and manually replace my files. I have all my data files off of the system on my NAS and have a Catalina bootable USB.

Will I have to manually rebuild the Fusion drive?

At some point I will break fusion drive and install 1TB NVMe and a 2TB SSD into this 2013 iMac.

 

[glenthompson]

As long as you don't break the fusion drive, formatting and reinstalling it for a new installation is the same as doing it on a single drive. Just go into Disk Utility and erase the Macintosh HD drive. The fusion drive will remain functional. Only way to split the fusion drive is via terminal commands.

 

[kirkster501]

Thanks for your help guys. I bombed the disk and reinstalled OSX this morning