I switched from Windows to CachyOS at the beginning of the year, and it has been working well overall. However, I now need Windows for some niche software that I only use occasionally. I have a year's worth of files, game installations, saved passwords, desktop customizations, and other configuration that I would rather not recreate. I also have a spare hard drive, but I would prefer not to dismantle my computer or risk damaging my current installation. What is the safest way to set up Windows alongside CachyOS?
4 Answers
Before changing the boot setup, make sure the important files and your boot configuration are backed up. It is also worth trying the software in Wine or a Windows virtual machine first, especially if it does not need direct hardware access. A VM is often enough for occasional use, but device communication, unusual drivers, DPI scaling, or demanding graphics can make it unreliable.
The lowest-risk dual-boot method is to install Windows on the spare drive with the existing Linux drive temporarily disconnected. Shut the computer down, unplug the Linux drive, connect the spare one, and install Windows normally. Afterward, reconnect the Linux drive and select it as the first boot device in UEFI. From CachyOS, regenerate the boot menu with os-prober enabled so Windows can appear as an option. You can also use the firmware's one-time boot menu to choose a drive directly.
If the software only needs Windows and does not require special hardware access, try running Windows in a KVM-based virtual machine first. For something used once every few months, that may be more convenient than maintaining a dual-boot setup. If it needs to communicate with old home-theater hardware or has broken scaling under compatibility layers, a real Windows installation on the spare drive is likely the least frustrating solution.
You do not necessarily need to reinstall or recreate your Linux environment. Another approach is to back up the EFI boot files, install Windows, and then restore or recreate the Linux boot entry afterward. That can work, but repairing the bootloader is more complicated than temporarily disconnecting the Linux drive, so the separate-drive installation is usually the simpler option.
This is generally safer than installing Windows while both drives are connected, since Windows is less likely to place its boot files on the Linux drive. Make sure you identify the correct disk during installation.