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I've read numerous articles that dance around this topic but haven't found anything specific about what I want to do. I have a brand new Lenovo desktop with two SSDs installed. It came with Windows 7 preinstalled and I've been using the machine for a couple weeks. Disk 0 contains the C: drive, which boots the machine. Disk 0 also contains a partition called "Lenovo_Recovery". Presumably I'd want to keep this in case things ever go bad. It also contains an "EFI System Partition". Can I use DISKPART to delete the EFI System partition and subsequently expand the main partition into this space and lose neither the data on my C: drive nor the ability to boot from it?

I haven't messed with partitioning disks since the DOS days (when a 40 MB hard disk was huge) and I'm just not sure what's possible now. I barely understand what EFI is or does. For what it's worth, I don't foresee ever booting multiple operating systems on this machine.

This question seems to ask the same thing, but the asker was planning to reinstall the OS. I don't want to do that.

Windows Disk Management reports as shown:

Disk Management Screenshot

The DISKPART utility shows this:

DISKPART Screenshot

  • Don't delete that partition. Even if you could will 100MB really make that much of a difference the Lenovo partition is more then useless though – Ramhound Nov 21 '15 at 0:11
  • This partition contains the Windows Boot Manager. Restoring it is a PITA. Also, you can't just extend a partition to include space located in front of it. – Daniel B Nov 21 '15 at 0:59
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No, do not delete this. It will probably ruin your computer if you do.

The EFI System Partition contains emergency boot files and allows your BIOS to boot using EFI. Your BIOS may allow legacy booting, but this requires a Master Boot Record.

I've experimented with this Partition before, and messing with it forced me to reinstall windows twice. If it is not a critical need, don't delete it.

  • It won't ruin anything but the ability to boot. ;) The UEFI firmware is entirely self-contained and does not rely on external storage like fixed disks. – Daniel B Nov 21 '15 at 0:54
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You should not delete "EFI System partition(ESP)" and not delete "MS Reserved partition" - they are critical for booting Windows.

On UEFI firmware (and GPT disks) boot files are stored on EFI System partition.

Windows uses MS Reserved for its own needs.

I suspect Lenovo Recovery is based on Windows PE (stripped Windows) so both mentioned partitions are needed.

For completeness UEFI boot sequence in short:

  1. After power up "UEFI firmware boot manager" is executed. It reads NVRAM variables and selects a boot candidate - a device(CD, DVD, USB) or an executable file stored on EFI System partition on hard disk.

  2. Usually this executable file is Windows UEFI boot manager (stored on EFI System partition) which is loaded and executed.

  3. Windows boot manager controls what happens next - either a boot menu is displayed or boot process continues directly with loading Windows loader, then Windows kernel and so on.

Note:

Microsoft has introduced yet another UEFI boot manager, also stored on ESP so we have following boot sequence: UEFI firmware boot manager, then Windows UEFI firmware boot manager, then Windows UEFI boot manager proper! The MS sentence explaining this "for simplifying boot process"........

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