Do I need the 3 UEFI partition?


  1. Posts : 7
    Windows 7 Ultimate x64
       #1

    Do I need the 3 UEFI partition?


    Hi all,

    I have read that if I pre-partionate my SSD before the OS install (in another computer or with command prompt (diskpart) by pressing SHIFT+F10 at the region/language selection window of the installer), it won't create automatically the 3 UEFI related partitions (Recovery, EFI-system, MSR Reserved) if the drive isn't unallocated.
    So three questions have born in my head immediately:
    1. What are these 3 partitions actually for?
    2. What do they do?
    3. Do I need them at all, if I want to see only C and D drives (1 drive with two partitions) in the Disk Management?

    Thanks,
    hazazs
      My Computer


  2. Posts : 34,931
    Win 10 Pro (1903) (2nd PC is 21H2)
       #2

    Example- EFI partition:
    Deleting EFI system partition will cause installed systems (to become) unbootable. So, EFI system partition is usually protected and locked by the Windows operating systems to prevent and avoid accidental deletion of these partitions. That's why you can't delete EFI partition using the Disk Management tool.
    How to Delete EFI System Partition in Windows 10/8.1/8/7/XP/Vista - EaseUS

    You can delete the Recovery partition. If you do, you cannot boot to Safe Mode having logged in to the OS, you lose automatic recovery (often not successful), and the ability to boot to advanced startup options e.g. Command Prompt, System restore

    What Is the System Reserved Partition and Can You Delete It?
      My Computers


  3. Posts : 17,266
    Windows 11 Pro
       #3

    Almost all UEFI computers need a FAT32 partition to boot from. That's why a separate EFI System Partition (ESP) is required. If you boot the computer in CSM (legacy BIOS) mode, then you can have your C: drive (NTFS) partition also be marked as Active and be the system partition the computer boots from. You will be limited to a 2 TB drive, because it will also have to be MBR partitioned to boot in CSM mode.

    What's the issue with having a small 100mb FAT32 system partition? It doesn't get a drive letter so it won't show up in explorer.
      My Computer


  4. Posts : 39,962
    windows 10 professional version 1607 build 14393.969 64 bit
       #4

    Windows is regularly updated.
    And Windows needs to have certain parameters to have a trouble free upgrade.
    There is little free space gained proportionally.
    There are many websites that offer free space in the cloud and large size flash drives and hard drives are relatively inexpensive.
    When you look at the pro and con its best to maintain the default partitions.

    https://docs.microsoft.com/en-us/win...ive-partitions
      My Computer


  5. Posts : 28
    Windows 10
       #5

    The EFI partition is needed for the system to boot and cannot be deleted.The MSR partition is used by some software that needs scratch space. I have read that bitlocker needs it. You will probably not notice any problem by not having it, however it is normally quite small (typically 16mb) so I would keep it; Microsoft says it is needed on GPT disk.The recovery partition is needed to boot in recovery mode (I think you can still boot in safe mode without it) which is a special very small live windows system that can be used for recovery. It contains a few automated tools that rarely works as well as a command prompt that may work if you know what to do. Even if you do not have it anymore, you can still have the same functionality by booting the official windows 10 media and choose "repair computer" instead of "install". IMHO, this recovery partition is not very useful. Some OEM might use a similar partition to factory reset the computer.
      My Computer


  6. Posts : 7
    Windows 7 Ultimate x64
    Thread Starter
       #6

    Guys,
    First of all, thanks for the infos (a reputation is given to everyone), but the question wasn't this: "Can I delete these partitions?"
    If a drive is pre-partitionated (means there is no unallocated space on it) then the OS install won't generate these partitions at all, even in UEFI mode.
    The question was: "Is this method "safe"?"
    I think in this way all the required boot/recovery files will be installed on the OS (C:) drive, right?

    By the way I don't really need that 615MB (499 + 100 + 16) space, simply IMO it's annoying such a lot of partitions.
    But finally I think I will let the installer creating them, since it is the default (maybe the most optimal) setting for a GPT style drive.
      My Computer


  7. Posts : 17,266
    Windows 11 Pro
       #7

    On an UEFI installation, the boot files cannot be in the C: drive partition. UEFI requires a FAT partition to boot from and C: drive will be NTFS.
      My Computer


  8. Posts : 7
    Windows 7 Ultimate x64
    Thread Starter
       #8

    Indeed. By the way why does this new UEFI boot mode use the old FAT system?
      My Computer


  9. Posts : 17,266
    Windows 11 Pro
       #9

    hazazs said:
    Indeed. By the way why does this new UEFI boot mode use the old FAT system?
    I don't know why the UEFI specification does not require EFI System Firmware to support NTFS, but it only requires it to support FAT. See starting on page 499 here:
    https://uefi.org/sites/default/files..._2_8_final.pdf
      My Computer


  10. Posts : 17,638
    Windows 10 Pro
       #10

    There's nothing in UEFI specifications preventing a PC booting from NTFS, if manufacturer has added correct firmware drivers. It's simply that older machines do not have necessary drivers.

    On my personal use, all my custom WIM deployment images are larger than 4 GB, making them too big to a FAT32 formatted USB flash drive. I format the flash drive, a single partition, with NTFS and boot my machines from it when installing or deploying. I have no issues in booting from this NTFS flash drive.

    Notice that Secure Boot must be disabled when booting from NTFS media.

    Please do not take the above wrong: I am not saying that it's OK to delete the FAT32 formatted EFI partition. On the contrary, it and MSR partition are important and should not be touched.

    Kari
    Last edited by Kari; 20 Oct 2019 at 04:28. Reason: Fixed some typos
      My Computer


 

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