Switching to Linux as my Daily Driver - (Part 1)

A step-by-step guide to safely install CachyOS alongside Windows in a dual-boot setup, with partitioning tips, EFI precautions, and guidance on how to reverse or remove it later.

 · 3 min read

Dual Booting Windows and CachyOS — Step-by-Step Guide

I want to dual boot my Windows with a Linux system

You ask why? It looks much more fun and exploratory. This is not an article on why I am changing in detail or my journey to this decision. This is just documentation on the process to dual boot with my existing Windows. Yes, I know, I would still need Windows — it has a way of pulling you back in for one thing or the other.

Why CachyOS?

I picked CachyOS — a variant of Arch Linux. I have tried it on an external hard drive and I believe I can cope now. Why Cachy? Well, they say it caches so it's faster. I partly agree but realized they played a trick on us. The kernel is not complete. I couldn’t even use iptables in the default kernel. That won’t be a problem for many users, and switching kernels is part of the learning process. You get a system you can tinker with and learn from.

The instruction below guides you through the dual boot installation. Disappointment alert: I generated this from ChatGPT — hopefully no hallucinations or dangerous assumptions.

Summary: A step-by-step guide to safely install CachyOS alongside Windows in a dual-boot setup, with partitioning tips, EFI precautions, and how to reverse it later.

🧭 What We’ll Cover

  • Preparation inside Windows
  • Bootable USB creation
  • BIOS / Boot setup
  • Safe partitioning
  • Installation (CachyOS installer)
  • GRUB + EFI handling
  • Reversal / recovery (if you change your mind)

🧭 1️⃣ Prepare Windows

✅ Back up first

Back up your important files to the cloud or an external disk. We won’t touch Windows, but mistakes happen.

✅ Disable “Fast Startup”

Prevents NTFS locks that confuse Linux:

Control Panel → Power Options → Choose what the power buttons do → Change settings that are currently unavailable → Uncheck “Turn on fast startup” → Save.

✅ Disable BitLocker (if enabled)

If your drive is encrypted, suspend or disable BitLocker before partitioning.

✅ Shrink your Windows partition

Right-click Start → Disk Management → Right-click C: → Shrink Volume → Leave unallocated space.

💽 2️⃣ Create CachyOS USB

🧰 You’ll need:

⚙️ Rufus Settings:

  • Device → your USB
  • Boot selection → CachyOS ISO
  • Partition scheme → GPT
  • Target system → UEFI (non-CSM)
  • Click Start

⚙️ 3️⃣ BIOS Settings (before boot)

Reboot → press F1 / F2 / F10 / F12 (depends on Lenovo) to enter BIOS.

  • UEFI mode: Enabled (not Legacy/CSM)
  • Secure Boot: Disabled
  • Boot order: USB first

💾 4️⃣ Recommended Partition Sizes

PartitionMount PointTypeSizeNotes
EFI (existing)/boot/efiFAT32Already exists (~100–500 MB)Do not delete — reuse it
Root/ext4 or btrfs80–100 GBOS, apps, updates
Home/homeext4 or btrfs100–150 GBUser data
Swapswap4–8 GBFor suspend/hibernate

Total suggestion: 200–250 GB for CachyOS, leaving plenty for updates and packages.

🧩 5️⃣ Install CachyOS

  1. Boot from the USB → choose “Boot CachyOS Installer”.
  2. If available, choose “Install alongside Windows Boot Manager.”
  3. If not, choose manual partitioning and use unallocated space.
  4. Select existing EFI partition (/dev/nvme0n1p1) → Mount point /boot/efiDo not format.
  5. Proceed — CachyOS will install GRUB and detect Windows automatically.

When done, reboot — you’ll see the GRUB menu with:

  • CachyOS
  • Windows Boot Manager

🪟 6️⃣ Post-install: Accessing Windows from Linux

sudo mkdir /mnt/windows
sudo lsblk
sudo mount /dev/nvme0n1p3 /mnt/windows
  

You can browse Windows files from your file manager and optionally set it to auto-mount in /etc/fstab.

⚠️ 7️⃣ If You Change Your Mind Later

  1. Boot into Windows.
  2. Open Command Prompt (Admin) and run:
    bcdedit /set {bootmgr} path \EFI\Microsoft\Boot\bootmgfw.efi
  3. Delete Linux partitions from Disk Management (right-click → Delete Volume).
  4. Optionally expand your Windows partition to reclaim space.
  5. To remove GRUB entry:
    bcdboot C:\Windows (or use EasyUEFI GUI tool)

The EFI entries are stored separately — removing GRUB or changing the default boot won’t break Windows.

🧠 8️⃣ Common Warnings

  • ❗ Never format or delete the EFI partition — just reuse it.
  • ❗ Install CachyOS in UEFI mode (same as Windows).
  • ❗ Turn off Fast Startup & Hibernation in Windows — otherwise Linux mounts Windows read-only.
  • ✅ Keep a Windows USB handy in case you ever need to repair boot.

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