macrumors member
Original poster
Jan 21, 2011
Hi everyone.

I received the new imac 27 this weekend, and he have the fusion drive.
I saw in the web that fusion drive makes automatically the variation of the programs between the ssd and the hdd, to keep the high velocity of access to the programs used at a moment by the user.

But i dont know if is possible to install programs only in hdd or only in the ssd, and if i can change that program between the hdd and ssd when i want.

Can i do it?

and when i install a program it will be saved at the hdd or in the ssd?



macrumors member
Original poster
Jan 21, 2011
No. It's fully automatic when it works in "fusion drive mode" and will shuffle apps depending on the frequency of use.

Oh thanks for the answer.

well is not possible to do something that can only run a program from the hdd, right?

you said "fusion drive mode", exist some other modes?
I will use a lot of logic pro and programming tools, for the logic pro it will be dangerous for the ssd, because of the writes that the logic pro will do.

Can i do something, or i will not have any problems with the fusion drive?



macrumors 68040
Dec 1, 2006
Cedar Rapids, IA. USA
Several options:

You can separate (break) the Fusion drive into separate SSD and HD and leave them that way.

You can break the Fusion drive, partition the HD as desired, then rebuild the Fusion with only part (1 partition) of the HD, leaving the rest of the HD out of the Fusion array's control.

You could add an external HD via Thunderbolt or USB 3.0 as large as you need.


Mike in Kansas

macrumors 6502a
Sep 2, 2008
Metro Kansas City
I'd use FusionDrive for a while before deciding the "break" it and use it in a traditional user managed SSD / HDD arrangement. What is neat about FusionDrive is that it is able to choose not just at the file or program level what gets stored on each disk, but at the block level. This means that if you use iPhoto, Aperture, or other apps that have a database managed as a "package", only the parts of that database that you use frequently will take up SSD space, while the rest of the database could reside on the HDD.

So for example, I have a 120GB Aperture library. It needs to reside on the SSD to give the best user experience; this library would basically consume the entire SSD portion of a stock Apple FusionDrive. However, the only part of the database that gets used frequently are the thumbnails of each project AND the images I frequently work on. All the rest can presumable reside on the HDD portion of the FusionDrive. I know that it is spanned across multiple drives as I can view each drive's activity in iStat Menus when I launch Aperture. When I begin to work on a different set of images, they will then presumably get moved to the SSD as the system recognizes that they are being touched more frequently.

Another area that is can be powerful is in the storage of apps. I've heard some say the entire Applications folder goes on the SSD. I do not know if that is true or not, but I hope not. I have many many GBs of apps in that folder that I may only use 1X to 2X a year; I would hope that they would reside on the HDD, and only get moved to the SSD if they begin to see use. Some users keep apps in multiple folders (some on SSD, some on HDD) in order to manage their storage; I like the idea of putting them all in one spot and let FusionDrive figure it out.

You can actually partition the FD without breaking it; it will create a HDD-only partition, along with an SSD/HDD FusionDrive partition. This may be useful if you want to force things onto the HDD that you NEVER want on your FD array (iTunes libraries, movie files, etc.). That way, your SSD usage would be maximized for things that REALLY need to be on it.


macrumors 68040
Mar 29, 2009
The whole reason they made Fusion Drive is so you don't have to worry about it.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.