Installing Ubuntu on a 2009 iMac in 2021

This is a post about installing Ubuntu Desktop (a Linux variant) on an iMac, including the problems I experienced, and how I overcame them, in case it helps some people doing the same. This just my personal experience, and not a tutorial.

For a while we have had an old iMac (21.5″ Late 2009) sitting around the house, unused. It’s so old, that there would be a serious security risk in using it, due to the lack of support, particularly security patches to the OS and other software, which can no longer be updated. I wanted an extra permanently installed computer available in a room that didn’t have one, mainly as a convenience, but it wasn’t worthy paying a bunch of money for a new PC.

Even though it’s obsolete for MacOS, it has more than enough power to run Ubuntu. With an Intel Core 2 Duo 64-bit processor and 4 Gigs of RAM, it comfortably meets the requirements for Ubuntu 20.04.2 LTS, the most version Long Term Stable release of Canonical’s desktop Linux distribution. There are of course plenty of Linux options for even older PCs.

The great thing about this model of iMac is the ample number of USB-A ports and ability to boot off a USB drive. So, I could create a bootable “live” USB drive. The first mistake I made was immediately booting from the live USB drive, and proceeded to partition my hard drive. I should have done the partitioning through MacOS. I split my 500 Gig hard drive into 2×250 Gig drives. One for MacOS and one for Ubuntu. The process actually ran for over 24 hours, and I thought I might have wrecked the existing OS installation. I have no idea where it hung, but surprisingly, after I did a forced power-off/on, the partitioning actually worked, while the MacOS partition remained. I had backed up everything, so I would have been fine. But, it was nice not to lose anything.

The installation after that was generally smooth. The major problem after installation was the NVIDIA graphics processor. The default open source driver (not made by NVIDIA) was buggy. The computer would arbitrarily freeze, sometimes briefly, and sometimes for a long time. There was no apparent reason for this, and it took a while before I could find the actual cause. So, following some online advice, I switched to the NVIDIA-made proprietary driver. That avoided most of the freezing, but created a small bit of visual static at the bottom of the screen, which became quite annoying. I switched back, getting the original problem again. The ultimate solution was to get rid of both drivers entirely (removing NVIDIA and disabling other). The iMac doesn’t actually need it. The NVIDIA processor speeds up graphics, but it’s not a noticeable effect for most tasks. An Intel processor exists, which handles what’s needed, just not as fast. I haven’t missed it, as I’m not a hardcore gamer or video editor, and if I was, I wouldn’t be using a decade old computer. Since then, the computer has been quite stable.

Ubuntu comes with the “Ubuntu Software” app, which lets you install various open software through the graphical desktop. For some reason, it only loaded selected “feature” software, but was otherwise empty. I had to do all installs from the command line. Fortunately, I found I could just install the Gnome Software manager to do the same thing, using the following command.

sudo apt update
sudo apt install gnome-software

A possibly minor problem, was every boot had a bunch of errors in the bootloader. I had to switch to the grub bootloader, instead of the one left by MacOS. After that, I could boot up without problem. I can’t start MacOS with grub, but I still have access to all of my files. I might be able to run MacOS again, by switching bootloaders again, but I’m not sure. Before taking on this task, I knew there was a risk, and backed up everything. So, I’m fine.

Overall I can do everything I want. I use Chrome’s Remote Assistant to let me connect to my Windows 10 in a different location, giving me the ability to do anything I’m been doing. It now works smoothly.