Success!
Just completed the update of this great machine, everything is working perfect in Yosemite!
Config:
2,7 GHz Intel Core i7
16 GB 1600 MHz DDR3
AMD Radeon HD 6630M 256 MB
DELL 2407WFP
DIY Fusion Drive Samsung 830 256 GB and Apple 500 GB 5400 RPM
I post my experience, in case it would be useful for anyone else.
1) How to install Yosemite with a Recovery partition on Fusion Drive
- Disable TRIM
First of all, you should disable TRIM. Just download TRIM enabler and deactivate it:
http://www.cindori.org/software/trimenabler/
Then force a back up from time machine. I did this in order to be 100 % sure that when I will migrate my Time machine back-up into Yosemite, TRIM will not mess up with the installation, since a clean install will require all your drivers to be signed. If you leave trim on and upgrade the system, for instance, you will not able to boot once you have finished to install Yosemite
- Creating the USB Installer for Yosemite
After downloading The Yosemite installer, you want to transfer it to a 8GB USB by opening the terminal and typing in the following command:
sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ OS\ X\ Yosemite.app
Be careful! On internet there are other methods which describe how to do this, however they will not preserve the Restore partition! The Apple document describing this command can be found here:
http://support.apple.com/kb/HT5856
- Preparing Fusion Drive for Recovery Partition
Second, you will restart your Mac, keep pressed the option button on the keyboard and select the USB stick as startup disk. You will land in the Yosemite installer. Now comes
the trick:
You open disk utility, select your fusion drive and do
not touch the partitions, or use weird terminal commands as other guides are suggesting!
Instead, you just
erase the present fusion drive, you quit disk Utility and start the installation process.
At the end it will leave you with "one second remaining" which in fact lasts more then ten minutes, I believe because of the recovery partition set up
- Recovering your data
You want just to start Migration assistent and import all your data from Time machine. I suggest also to repair disk permission as the installer of Yosemite is not that clean...
2) Activate Trim
Download the most recent version from cindory, install and start trim enabler:
http://www.cindori.org/software/trimenabler/
You must restart the mac two times in order to activate it. The first one will remove the Kext signature required by default by yosemite, the second one to actually start Trim. Some users are worried by touching this setting in Yosemite, but I believe that if you don't download daily unknown apps from the internet, the risk is acceptably low.
3) Activate continuity and Handoff by downoading and running continuity activation tool, created by Dokterdok a MacRumors forum user:
https://github.com/dokterdok/Continuity-Activation-Tool/
Restart and enjoy your Mini!
I am not sure if this is because of the fast DDR5 VRAM integrated 6630 Graphics, or the 16 GB of Ram, but Yosemite on my mini seems snappier here than on the mac book pro 2013 of my girlfriend with 8 GB Ram...
