How to Upgrade the Main Drive in a 21.5-inch iMac 2017

The Rocket Yard and have long encouraged the do-it-yourself philosophy when it comes to upgrading your devices. And with our extensive catalog of instructional videos, we help make it possible for users to perform the upgrades they need themselves.

We are always working hard to expand our catalog of step-by-step instructional videos, and after adding a video demonstrating how to install memory in the new 2017 21.5-inch iMac with Retina 4K display, we’ll now show you how to upgrade the same model’s main drive.

Related: Rocket Yard Guide: iMac DIY vs. Apple Repair

Upgrade beyond the factory 2.5-inch 1.0TB hard drive ceiling and install a hard drive up to 3.0TB, or for the ultimate performance upgrade, swap the main hard drive out with a SSD up to 2.0TB. Utilize our install video to guide your upgrade step-by-step and make your iMac faster than from the factory.

Note: Professional installation is recommended for this upgrade due to the complicated process.

Fusion Drive Note: If you’re upgrading a Fusion Drive equipped iMac you will need disable the Fusion Drive first, and then, if desired, create a Fusion Drive with the new drive after the upgrade is performed. You can learn how to do that at:…


  • Wanted to upgrade the Fusion drive from 1TB to 2TB in the 21.5″, 3.4GHz, as you can in the 27″, 3.4GHz iMac. Apple say that this cannot be done pre sales as it is not an option on 21.5″ Why? Is it easy to replace the Fusion drive in the 21.5″?

  • So, does this hard drive upgrade not require the adapter used in the slightly older iMac to account for the Apple firmware heat sensor issue?

  • Is the controller seriously limited to just 3TB???? With 4TB to 10TB drives readily available, is this really a hard limitation?

    • never mind; just realized these are 2.5″ drives. Another reason I’ll never buy an iMac. If I want a laptop computer with expensive, limited, lower-performing laptop components, I’ll buy a laptop.

      • The small iMac takes 2.5″ drives, but the larger version (27″) takes 3.5″ drives so you can go high-capacity if you want. The best thing about these is adding the additional SSD and making a fusion drive, so you end up with a super-fast machine as well as tons of storage. But as for the little 21.5″ iMacs, because you’re replacing a laptop drive, the gains from going SSD are really impressive. I’ve upgraded lots of these for my clients, they’re always amazed at how much faster their Macs are than even when they were new!

      • Hi Frederico. You should always do what’s right for you. But that being said, I’ve worked with both Windows, Unix pretty much all my life. As you know, MacOS is based on Unix.

        You are right that Apple does tend to choose more conservative components…unless you also want to count the iMac Pro…and they are expensive. But a lot of what I no longer do, now that I’ve switched to Apple is worry. I don’t worry about malware. Yes, there is some (few) written for Unix, but a little common sense takes care of those. I don’t worry about filesystem issues. I don’t worry about defragmentation. I don’t worry about the “registry”. If you choose to delete a program on a Mac, you go to Applications and press the Trash button. Can you do that on Windows 10? I doubt it. You have to worry about all the different places that the program puts stuff under the Windows OS. I don’t worry about anything, really.

        I’m just offering a different perspective. You’re right, it’s expensive and yes, you’re right that it is lower performing and you can’t easily, if at all, upgrade the various parts (graphics card, CPU, motherboard) and actually those things are not even possible. But with the help of MacSales, I’ve increased my RAM and sped up my 2009 Mac-mini so that I still really enjoy using it. My only gripe is that I can’t upgrade the graphics. So I’ll end up purchasing a new iMac soon.

        I also no longer worry about drivers, and constantly going into and out of the system box, making sure the power supply is sufficient, making sure I download hot fixes every other day or the various SP’s. I don’t miss any of that.

        I hope this help provide a different perspective. :-)

        • Nathan, when you throw out an application on a Mac you can still land up with files you don’t need. But if you get a piece of software like AppTrap, which is what I use, your Mac will ask if you want to throw out other files associated with the application you are getting rid of. AppTrap is free. Look for it on

  • What about iMac 27″ 2017 with Retina 5K display?