/LinuxOSCommonz

1. EFI System Partition (ESP)

  • Size: 100–500 MB (Windows usually creates ~100 MB, Linux installers often recommend ~300–500 MB).
  • File system: FAT32.
  • Partition type in GParted: EFI System Partition (or just FAT32 and mark it with the boot, esp flags).
  • Mount point (in Linux): /boot/efi.
  • Purpose: Stores the EFI bootloaders (Windows Boot Manager, GRUB, etc.). Both Windows and Linux share this partition.

2. Windows Partitions

  • Windows main system partition (C:):

    • NTFS, usually 50+ GB.
    • Contains Windows OS and installed programs.

  • Windows recovery partition (optional, but Windows usually creates one):

    • NTFS, ~500 MB–1 GB.
    • Holds recovery tools.

(If you’re restoring from scratch, Windows will recreate these during installation, but you need free space set aside for it.)

3. Linux Partitions

  • Root (/):

    • ext4 (most common).
    • 20+ GB recommended.

  • Swap (optional):

    • Equal to your RAM if you want hibernation; otherwise 2–4 GB is usually fine.

  • Home (/home) (optional but recommended):

    • ext4.
    • Stores user files separately from system files.

4. Microsoft Reserved Partition (MSR) (for Windows on GPT)

  • Windows often requires a small (16–128 MB) unformatted MSR partition right after the EFI partition.
  • GParted will show it as “unformatted” space.
  • Windows installer usually creates this automatically, but if you’re restoring manually, you can create it (unformatted, no filesystem, just mark it as MSR).

✅ Summary (minimum working layout):

  1. EFI System Partition – FAT32, 300–500 MB, flagged as boot, esp.
  2. MSR (Windows only) – 16–128 MB, unformatted.
  3. Windows partition – NTFS.
  4. Linux root (/) – ext4.
  5. (Optional) Swap, Home, Recovery partitions.

⚠️ Important:

  • If Windows is already installed, don’t recreate the EFI partition (it contains EFI/Microsoft/Boot/bootmgfw.efi), just reuse it and add GRUB alongside it.
  • If both OSes are gone and you’re restoring from scratch, create the EFI partition first, then install Windows, then Linux (Linux installer will detect Windows and set up GRUB).

🔹 What is the MSR?

  • The MSR (Microsoft Reserved Partition) is a tiny partition that exists only on GPT disks when installing Windows.

  • It does not contain a filesystem (so GParted shows it as “unformatted”).

  • It’s used internally by Windows for partition management:

    • To reserve space for converting basic disks to dynamic disks.
    • To allow Windows to create hidden partitions (like recovery or shadow copies) later.
    • Acts as a placeholder for future use by Windows.

🔹 Size

  • Windows 10 / 11: 16 MB
  • Older Windows (7/8): 128 MB
  • Location: Right after the EFI System Partition (ESP), before the main Windows NTFS partition.

🔹 Do you need to create it manually?

  • Normally, no. If you install Windows on a GPT disk with unallocated space, the installer will create the MSR automatically (alongside the EFI partition, recovery partition, and the main NTFS partition).

  • If you’re restoring manually with GParted (e.g., recreating a GPT layout from scratch), you can create it yourself:

    • Make a partition of 16 MB (or 128 MB if you want to be extra compatible).
    • Leave it unformatted (don’t assign FAT32/NTFS).
    • You don’t need to set special flags — Windows will recognize it.

🔹 What happens if it’s missing?

  • Windows may still install and boot, but it might:

    • Fail to upgrade cleanly.
    • Fail to create certain system partitions.
    • Have issues with disk management features (like converting to dynamic disks).

So it’s best to have it.

🔹 How it fits in dual-boot

A clean GPT dual-boot structure (Windows + Linux) looks like this:

  1. EFI System Partition (ESP) – FAT32, 300–500 MB, flagged boot, esp.
  2. Microsoft Reserved Partition (MSR) – 16 MB, unformatted.
  3. Windows OS (C:) – NTFS, 50+ GB.
  4. (Optional) Windows Recovery Partition – NTFS, ~500 MB–1 GB.
  5. Linux root (/) – ext4, 20+ GB.
  6. Linux swap – optional.
  7. Linux home (/home) – optional.

👉 So in short: the MSR is just a tiny “reserved slot” for Windows on GPT disks. You don’t interact with it directly, but it helps Windows stay happy long-term.