Step by step of installation fusion drive on mac

[parisinvest]

i've just upgrade my imac 27 2015 5K, this method can be use on all model mac supported by el capitan offically, and i share it here for whom want to do it too, but please read all of these steps before you start to proceed, first for preparation you need:

imac lcd open wheel
https://www.amazon.com/iMac-Opening...qid=1530919190&sr=8-10&keywords=imac+tool+kit

one screw driver kit
https://www.amazon.com/Smraza-Preci...&qid=1530919190&sr=8-4&keywords=imac+tool+kit

suction cups
https://www.amazon.com/Suction-Kais...&qid=1530919190&sr=8-5&keywords=imac+tool+kit

for more comfortable to work, one imac service wedge
https://www.amazon.com/iMac-Two-One...qid=1530919190&sr=8-17&keywords=imac+tool+kit

and of course a ssd for mbp retina 2013, which is the same for imac 2015, at least 128go, i took the 256go with only 30 euros difference
a hdd sata III 7200 tour, seagate or western digital, i like toshiba too, anyway the marque is not important, they are all same for me, 3go or 4go it's up to you

for openning imac and installation ssd and hdd sata, you have youtube shows a lot, i dont want to repeat here. but most important thing is when you upgrade the ssd and the hdd, they will show as two parts of storage in disk utility, now you need follow the steps below to get back your fusion drive option, which is a better organisation, and better speed specially:

btw if you have mac 2009 or later, i didnot try on 2008 model, but i'm pretty sure all models support el capitan can install the method, but you may want to go app store to download YOUR system installer dmg, https://itunes.apple.com/app/os-x-el-capitan/id1147835434?mt=12, the thing is if you use the installer downloaded from other machine, specially el capitan, it wont work in a easy way: drag to usb and restart the mac from step "1", because your mac will recognize only the installer from YOUR MAC's own app store.
but somehow you did not have the system installer downloaded from your mac, you can still use other installer (must store it in "Application" folder in mac), and type in terminal:
sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/YOURUSBNAME --applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app --nointeraction
replace "yourusbname" by your usb name, your usb must be bigger than 8go, and enter, the proceed will take 5 to 10 minutes, that will do the usb bootable system to install after step "6".

after close your lcd on, dont attach the colle right away, use some scotch to keep the lcd, make sure you have tested for at least one week to colle the band sticker：

1, start the imac with holding commande+r till apple logo appears, you will enter the recovery mode, connect to your wifi, and download the os from apple server, if you have already your el capitan usb installer, (some model before 2012 provide only lion from apple server, which will not work for our fusion, so you have to prepare an usb installer which i showed the way to do above), please start from your usb, dont try to install sierra or high sierra directly, it may not work cause the compatibility, the os propose by apple is el capitan, after download, you will enter to desktop of recovery mode.

2, open terminal, type "diskutil list" enter, you will see all your disk, remember which are two you want to fusion, normally is disk0 and disk1

3, type in terminal: "diskutil unmountDisk disk0" and then "diskutil unmountDisk disk1" , these make sure you unmount your both disk to be ready to do the fusion

4, type "diskutil cs create Macintosh\ HD disk0 disk1", this will take sevral seconds, it depends on your disk size
exception: in some cases, this operation cant accomplised, this may provient de ssd, in this case use a external usb may solve the error problem, (search yourself how to make bootable USB system on mac, in simple: just drag the app store version system disk image to usb, it will directly start from usb cause the disk were empty), and repeat from "2", but recommanded install el capitan first then upgrade to high sierra from app store

5, type "diskutil cs list" , to see the new disk volume, remember the numbers after "Logical Volume Group", it's like '8354AFC3-BF97-4589-A407-25453FD2815A' , copy it with command+c

6, type in terminal "diskutil cs createVolume YOURNUMBERS jhfs+ Macintosh\ HD 100%" , when it's done, quit terminal, start reinstall os x, you will see only one macintosh hd as disk, so install it and after restart and finish your installation, you will get into the desktop, in the 'about this mac' you will see your fusion drive, and mine speed is 1800m/s

7, you can start to install your apps and games, and you can upgrade to high sierra now as usual

i've tested this method on my mbp 2011 too, and it worked, basicly you can combine any size of capacity ssd and hdd, enjoy it !