Let me bore you with the story of my current computer…
As my late 2009 iMac was getting a bit long in the tooth I decided last year to get rid of the optical drive and in its place install an SSD.
I did do the upgrade and of course screwed up.
While reassembling a screw fell into the gaps and after retrieving it I reconnected all the cables again and in doing so almost ripped out one of the connectors. I was a pretty shocked and pissed with myself since I voided the last two months of my extended warranty but decided to still continue.
It seemed that I managed to not screw up to much but somehow the thermal sensor of the display was busted and therefore the fan decided to run in default mode (i.e. 2500 rpm). Only then I realised that my iMac can be pretty noisy. A few noisy and stressful hours of research and configuring later the Computer was whispering again.
I used smcFanControl and a shell script to set the fan speeds manually.
As this screw up was enough for the moment I did not dare to turn the two disks into one Fusion drive.
I also stuck with Mavericks because I am using GPGMail and had bad experience with the upgrade of the previous two or three OS Versions.
Fast forward to a few weeks ago. I finally decided to try the Fusion on my system.
After making sure my Time machine Backup was up to date I also made a backup using “SuperDuper!” as it always is good practice to have alternatives. I’ll write about Backups another time though.
I then downloaded the latest Mavericks version and made myself a USB Boot Disk.
I was able to boot and create a FusionDriveGroup but for whatever reason the Installation of Mavericks failed.
On a whim I then decided to upgrade to Yosemite. So I got the latest version of it on my MacBook and created yet another USB Install Disk.
This time it worked like a charm and I am now the proud owner of a 1.5 TB FusionDrive as you can see below.
Well proud and paranoid as I read in the posts helping me with the installation that if one of the two involved disks fail EVERYTHING fails.
If you are interested in the details of How the Fusion drive part I followed these two post:
http://benscheirman.com/2013/11/creating-a-fusion-drive/
and
http://www.macworld.com/article/2014011/how-to-make-your-own-fusion-drive.html