I have an iMac 21.5 inch, Late 2013, Catalina (10.15.8) memory 16GB 1600 MHz DDR3.
It is in good order but has become very slow and updates are no longer provided so many apps can no onger run on it.
It has Bootcamp installed, with Windows 10 which I no longer need.
I would like to replace Windows 10 with Linux. How do I do this? I would also like to give Bootcamp more space and Catalina less.
iMac 21.5″, macOS 10.15
JWood42 wrote:
I have an iMac 21.5 inch, Late 2013, Catalina (10.15.8) memory 16GB 1600 MHz DDR3.
It is in good order but has become very slow and updates are no longer provided so many apps can no onger run on it.
It has Bootcamp installed, with Windows 10 which I no longer need.
I would like to replace Windows 10 with Linux. How do I do this? I would also like to give Bootcamp more space and Catalina less.
Before you do anything to your iMac, I highly recommend you first backup all of your important files. If you may need to access those files on Linux, then make sure you store those files on media that can easily be accessed by Linux such as an exFAT file system or a NAS.
Second, you should create a bootable macOS Catalina USB installer now while you still can do so. While your iMac should be able to use Internet Recovery mode (Command + Option + R) to reinstall macOS later on......many people tend to have issues due to poor networking conditions and also the poor state of Apple's online macOS installers these days. Better safe than sorry. I would even recommend booting from the macOS USB installer as well.
Do you know whether your iMac is using an internal Hard Drive, an internal SSD, or a Fusion Drive (a combination of an internal HD & SSD)? If this iMac is supposed to have a Fusion Drive, then you should verify the Fusion Drive is still intact.
You should also verify the health of the internal drive(s) by using the third party app DriveDx (free trial period). Feel free to post the complete DriveDx text report(s) here using the "Additional Text" icon which looks like a piece of paper on the forum editing toolbar. I will be happy to check those reports. Generally if a Hard Drive report shows any "Warning" or "Failing" notices, then that Hard Drive should not be used because it is worn out or failing respectively. The same is not always the same for an SSD which requires manually interpreting the SSD's health report.
If the internal HD is worn out or failing, then it is not worth installing Linux on the internal HD. However, if your iMac has a Fusion Drive, then utilizing the SSD portion may be an option if it is a 120GB SSD. Otherwise, @jeffreythefrog is correct in suggesting an external drive. An external drive is also a good option if you would like to leave your macOS installation untouched until you are sure you wish to fully remove it.
If the internal drive is healthy, then you can remove Windows as suggested by @jeffreythefrog. Afterwards you can use Disk Utility in macOS to resize the macOS partition/Container to make a new partition for use with Linux. In order to use that new partition for Linux, you will need to have the Linux installer select that partition (may actually need to have the Linux installer delete that new partition & use the free space for the Linux install).
If you are not familiar with Linux, then I would suggest using Linux Mint since it should just work on the iMac and it can be a bit more user friendly in the beginning. While most x64 Linux distributions can work on a Mac, some of them may not always work right out of the box due to issues with their bootloaders & some quirky behavior of Apple's firmware (the installer usually works, but the first reboot into the new OS can sometimes fail depending on the Apple firmware & how the Linux distribution handles their bootloaders).
As long as you have a bootable macOS USB installer, then you should be able to easily return to macOS if you encounter any issues or if you realize Linux is not for you.
JWood42 wrote:
I have an iMac 21.5 inch, Late 2013, Catalina (10.15.8) memory 16GB 1600 MHz DDR3.
It is in good order but has become very slow and updates are no longer provided so many apps can no onger run on it.
It has Bootcamp installed, with Windows 10 which I no longer need.
I would like to replace Windows 10 with Linux. How do I do this? I would also like to give Bootcamp more space and Catalina less.
Before you do anything to your iMac, I highly recommend you first backup all of your important files. If you may need to access those files on Linux, then make sure you store those files on media that can easily be accessed by Linux such as an exFAT file system or a NAS.
Second, you should create a bootable macOS Catalina USB installer now while you still can do so. While your iMac should be able to use Internet Recovery mode (Command + Option + R) to reinstall macOS later on......many people tend to have issues due to poor networking conditions and also the poor state of Apple's online macOS installers these days. Better safe than sorry. I would even recommend booting from the macOS USB installer as well.
Do you know whether your iMac is using an internal Hard Drive, an internal SSD, or a Fusion Drive (a combination of an internal HD & SSD)? If this iMac is supposed to have a Fusion Drive, then you should verify the Fusion Drive is still intact.
You should also verify the health of the internal drive(s) by using the third party app DriveDx (free trial period). Feel free to post the complete DriveDx text report(s) here using the "Additional Text" icon which looks like a piece of paper on the forum editing toolbar. I will be happy to check those reports. Generally if a Hard Drive report shows any "Warning" or "Failing" notices, then that Hard Drive should not be used because it is worn out or failing respectively. The same is not always the same for an SSD which requires manually interpreting the SSD's health report.
If the internal HD is worn out or failing, then it is not worth installing Linux on the internal HD. However, if your iMac has a Fusion Drive, then utilizing the SSD portion may be an option if it is a 120GB SSD. Otherwise, @jeffreythefrog is correct in suggesting an external drive. An external drive is also a good option if you would like to leave your macOS installation untouched until you are sure you wish to fully remove it.
If the internal drive is healthy, then you can remove Windows as suggested by @jeffreythefrog. Afterwards you can use Disk Utility in macOS to resize the macOS partition/Container to make a new partition for use with Linux. In order to use that new partition for Linux, you will need to have the Linux installer select that partition (may actually need to have the Linux installer delete that new partition & use the free space for the Linux install).
If you are not familiar with Linux, then I would suggest using Linux Mint since it should just work on the iMac and it can be a bit more user friendly in the beginning. While most x64 Linux distributions can work on a Mac, some of them may not always work right out of the box due to issues with their bootloaders & some quirky behavior of Apple's firmware (the installer usually works, but the first reboot into the new OS can sometimes fail depending on the Apple firmware & how the Linux distribution handles their bootloaders).
As long as you have a bootable macOS USB installer, then you should be able to easily return to macOS if you encounter any issues or if you realize Linux is not for you.
The only tool in the world that can remove that Boot Camp partition is Boot Camp. Otherwise, at some point, you will need to reformat the entire drive to reclaim that Boot Camp partition storage and rebuild the partition map.
Once the first paragraph is done, I would strongly recommend installing a free VM that remains compatible with macOS Catalina:
Each of these can take a Linux ISO live installer and build a VM guest operating system. One that you can run concurrently with macOS. I would not recommend Ubuntu 26.04 LTS or Ubuntu Cinnamon 26.04 LTS as they are (in my own experience) incompatible with current VM versions and older VMs almost certainly have no support for current Linux distros.
With a Virtual Machine guest, you should not assign more than half your available RAM, nor more than two CPUs from that 21-in iMac to the guest.
In my opinion, attempting to install Linux onto Mac hardware as a dual boot solution without going the Virtual Machine route is asking for virtually unsupported trouble and lost time.
JWood42 wrote:
It has Bootcamp installed, with Windows 10 which I no longer need.
you can boot into macOS, and then open bootcamp assistant and remove it from the Mac. that will give the whole drive back to macOS.
I would like to replace Windows 10 with Linux. How do I do this? I would also like to give Bootcamp more space and Catalina less.
as far as installing Linux, if you know someone with linux on their machine, and have a spare external SSD, the easiest thing is to have the external drive formatted to EXT4 on the linux machine. and then you can use a linux bootable media usb stick and install linux on to the external. and you can create the bootable media using balenaEtcher directly on your Mac, and install linux on the SSD with the usb stick. (also from your Mac) no need for bootcamp or a VM.
this would especially be my recommendation if the Mac is HDD based. Linux would prefer an SSD.
jeffreythefrog wrote:
as far as installing Linux, if you know someone with linux on their machine, and have a spare external SSD, the easiest thing is to have the external drive formatted to EXT4 on the linux machine. and then you can use a linux bootable media usb stick and install linux on to the external.
FYI, there is no need for another Linux system or to even prepare the external drive before using the Linux installer. The Linux installer will usually give the user several options on how to deal with the desired destination drive with one of them being to use the entire drive.
HWTech wrote:
FYI, there is no need for another Linux system or to even prepare the external drive before using the Linux installer. The Linux installer will usually give the user several options on how to deal with the desired destination drive with one of them being to use the entire drive.
thanks for letting me know that. when I first wanted to try and install linux on an external drive, I was relying on google for my info. so that is why I thought the drive needed to be formatted first on a linux machine. fortunately for me, I had one.
this would especially be my recommendation if the Mac is HDD based. Linux would prefer an SSD.
FYI Linux Mint runs exceedingly well on a 2008 iMac with its original hard disk. That drive also happens to have Snow Leopard and El Capitan. Triple-boot with lots of room to spare.
Linux is extremely efficient. So were earlier macOS versions.
Mint is also installed on a 2011 iMac with an OWC SSD. The speed difference is not significant.
yes, I get that. and linux does run very good on older hardware, including HDDs. an SSD is not an absolute necessity. but I would still recommend an SSD to run linux. especially if you already have a spare external SSD.
JWood42 wrote:
Thanks to everyone who has contributed to this. All very useful. And I'll welcome any further comments too.
you're welcome. :)
I'll let evryone know how I get on
yes, please do. :)
Thanks to everyone who has contributed to this. All very useful. And I'll welcome any further comments too.
I'll let evryone know how I get on
iMac: Install Linux over Bootcamp, resize partitions
