Windows 10 bootable USB has 2 UEFI patitions?

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  1. Posts : 18,424
    Windows 11 Pro
       #11

    No offense, @Akeo, but the Microsoft Media Creation Tool creates an MBR partitioned USB flash drive with a FAT32 partition marked as active on it for a reason. That reason being is that it is universally bootable on legacy BIOS systems, UEFI systems, and UEFI system in CSM mode. If the user wants only a standard Windows 10 installation USB flash drive there is absolutely no reason to create it in any other format. And the other advantage is there is no need to disable Secure Boot in UEFI if the user wants to leave it enabled.

    Also the current Windows 10 ISO files from Microsoft contain install.esd files that do fit within the 4 GB file size limit of FAT32 so your statement ,"1. The latest Windows retail ISOs contain a file that is larger than 4 GB, therefore FAT32 cannot be used as is" is erroneous.
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  2. Posts : 31,468
    10 Home x64 (22H2) (10 Pro on 2nd pc)
       #12

    Akeo said:
    1. The latest Windows retail ISOs contain a file that is larger than 4 GB, therefore FAT32 cannot be used...
    That is only true if the ISO contains an install.wim. An ISO made by the Media Creation Tool will contain an install.esd. The ESD format is more compact and will be less than 4GB, so Fat32 can be used. Generally, only when you download an ISO directly from Microsoft will it contain an install.wim.

    The current ISO made by the MCT is for 1809 build 17763.253 and has a 3.26GB install.esd.

    Windows 10 bootable USB has 2 UEFI patitions?-image.png
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  3. Posts : 29
    Windows 10 x64
       #13

    D3SOL4TE said:
    I think I tried booting from "Partition 1" and while it appeared to work I wasn't sure if it would cause any issues?
    Pity. Maybe you should place a little bit of trust in people who have been spending the last 5 years designing software that ensures that you can boot and install Windows exactly as if you were doing so from a DVD media...

    For future reference providing it will even boot to begin with does it actually make any difference whether I boot from Partition 1 or 2?
    It shouldn't. If both partitions are being proposed, it means that your UEFI firmware can boot either because it contains its own NTFS driver (which again, almost all recent firmwares from major vendors do).

    As a matter of fact, if you have Secure Boot enabled, you may even be able to boot from that first partition without disabling it.

    NavyLCDR said:
    but the Microsoft Media Creation Tool creates an MBR partitioned USB flash drive with a FAT32 partition marked as active on it for a reason.
    Sigh. And Rufus creates a FAT partition with the UEFI NTFS driver for the same reason, i.e. so that it can cater for UEFI systems that don't handle NTFS natively.

    That reason being is that it is universally bootable on legacy BIOS systems, UEFI systems, and UEFI system in CSM mode.
    So this is one first point where you are wrong. BIOS + UEFI boot only depends on the partition scheme used being MBR. The provision of a FAT file system, so that UEFI systems that don't include an NTFS UEFI driver can also boot that drive, can be provided as a courtesy for people who are going to use that drive on UEFI systems where NTFS support is not provided (or if they don't know), but, by all means, it is not necessary.

    For instance, if you are only going to be booting relatively recent intel NUC systems or ASUS or Gigabyte motherboards, which all include NTFS support in their UEFI firmware, there is absolutely no reason to create a FAT32 drive, and you can absolutely work with an MBR partitioned drive with a single NTFS partition, and that drive will be BIOS + UEFI + UEFI-CSM compatible.

    Also, and this is something that I will invite everybody who wants to dispute the statement that the Windows installation partition should be created a FAT32 with the active flag, you can very much create BIOS + UEFI + UEFI-CSM "universal" bootable USB drives in Rufus if you use the Alt-E cheat mode (and make sure you use MBR as the partition scheme), even as the main partition with the install.wim is NOT FAT32 but NTFS.

    The thing is, while Rufus will let you create dual BIOS + UEFI bootable drives, it does not do so by default, for the reasons explained here (different design philosophy from Microsoft here, not a technical limitation), but this can easily be changed through using Alt-E in Rufus.

    So, I can demonstrate, with proof, that your "Only MCT with FAT32 can be used if you want dual BIOS + UEFI boot" statement is factually wrong.

    If the user wants only a standard Windows 10 installation USB flash drive there is absolutely no reason to create it in any other format.
    Oh but there is.

    Contrary to what you assert (which is another easily verifiable statement), the RETAIL Windows 10 1809 ISOs contain an install.wim that is larger than 4 GB.

    And if you do like security (i.e. if you care about Secure Boot and whatnot), there is a huge advantage with using the retail ISOs over the MCT, because you can validate, through SHA verification, that your initial installation media is both official and has not been corrupted.

    And the other advantage is there is no need to disable Secure Boot in UEFI if the user wants to leave it enabled.
    Addressed once again in the FAQ.

    Please don't make it look like Rufus asks you to disable Secure Boot for anything but just the initial boot (and only because Microsoft does not want to sign GPLv3 code - nothing more nothing less).

    There isn't a single x86 based system in existence where you can't temporarily disable Secure Boot in the settings, and, if you have validated that you are using an official ISO, through an SHA check (which Rufus can do), the use of Secure Boot for that initial boot is a bit superfluous, so temporarily disabling it is not a security risk.

    Also the current Windows 10 ISO files from Microsoft contain install.esd files that do fit within the 4 GB file size limit of FAT32 so your statement ,"1. The latest Windows retail ISOs contain a file that is larger than 4 GB, therefore FAT32 cannot be used as is" is erroneous.
    No, it's you who are wrong.

    You're only considering the ISOs created by the MCT, and not the RETAIL ISOs, which are also widely used, and can easily be obtained either from MSDM or from Download Windows 10 Disc Image (ISO File)

    Please go to Download Windows 10 Disc Image (ISO File), download a 1809 ISO, and tell me whether install.wim is not larger than 4GB:

    Windows 10 bootable USB has 2 UEFI patitions?-image1.png
    en_windows_10_consumer_edition_version_1809_updated_sept_2018_x64_dvd_491ea967.iso (SHA-1 bee211937f3ed11606590b541b2f5b97237ac09d)

    Note however that, if you try this from a Windows 10 system, you may have to change your User-Agent string to make it look like you're browsing from an earlier version of Windows, or a Linux or Mac system, otherwise the Microsoft website is designed not to let you download the retail ISO (which is very stupid, as, these are the ones whose SHA-1 can be easily validated), but direct you to the MCT instead.

    Still, if you don't want to fiddle with the User-Agent string, you can also go through TechBench by WZT (v4.1.1) which will let you download the same ISOs, from the Microsof download servers, even if it's not a site that is affiliated with Microsoft.

    So, to reiterate:

    1. No, there is no need for a FAT32 partitioned drive to achieve BIOS + UEFI + UEFI-CSM compatibility
    2. Not all Windows 10 1809 ISOs contain an install.[wim/esd] that is smaller than 4GB. For now, only the MCT created ISOs do, but the RETAIL ISOs certainly don't. As such, for people who want to use the retail ISOs (for instance to ensure that the image they work with has not been altered in any way, but there are plenty of other reasons why people may want/need to use retail ISOs insted of MCT ones), FAT32 becomes impractical.

    So please get your facts straights instead of continuing the propagate this hard to kill bullshit that only FAT32 will ever do.

    Oh, and please have a closer look at what Rufus does or can do (such as creating dual BIOS + UEFI bootable drives - by the way, this also includes dual BIOS + UEFI bootable Windows To Go drives) before declaring that there can be only one way to achieve something.
    Last edited by Akeo; 20 Feb 2019 at 05:13.
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  4. Posts : 18,424
    Windows 11 Pro
       #14

    Let's put it this way.....I've had to help enough people on this forum because their USB flash drives created with Rufus would not boot in their computers that I don't recommend it for people with less experience who have a propensity for not getting all the settings correct in it. Rufus just simply is not required in any way shape or form to create a standard Windows 10 installation USB flash drive. Rufus is a great program for more experienced users who want to do something custom with their flash drives. But for the user who wants nothing but the standard Windows 10 installation drive, Rufus is absolutely not necessary. And that is a myth that needs to be debunked - that some special program is required to make a bootable Windows 10 flash drive.
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  5. Posts : 29
    Windows 10 x64
       #15

    Well, considering that I'm not limiting myself to only trying to help people on a specific forum, I do have of course a different view as I do tend to get reports from users who are using the Windows retail ISOs. I am also a bit concerned that, for someone who's supposed to be familiar with the matter, you didn't seem to be aware that the latest 1809 retail ISOs were completely unusable for a straight FAT32 copy. So you'll excuse me if, even as you stated that you helped a lot of people, I am not coloured impressed when the first thing you did in this thread, when someone who wasn't running into an actual issue and could have installed their Windows 10 media just fine, was to assume that Rufus had done something wrong (on account that it was simply doing something you didn't seem to be aware of or knew was achievable).

    As such, I can't help but wonder how many of your "because their USB flash drives created with Rufus would not boot" stemmed either false assumptions there again, or, possibly, because you didn't take into account that Rufus is designed differently from the MCT and, as opposed to the MCT, it does request the user to make sure they choose whether the target they want to Windows install on is BIOS or UEFI.

    I also have to wonder: Have you ever tried to help the people who were using Rufus complete the process with Rufus itself? For instance, have you pointed them to FAQ entries such as this one? Or did you instead decide that, as you are also asserting here, it's your duty to tell people who are trying to use Rufus to ditch it, instead of trying to actually help them?

    I hope you can understand why I do have a slight issue with your "(there's no need for a) special program (...) to make a bootable Windows 10 flash drive", when, since Microsoft does advertise it, people also tend to use the retail ISOs they can download from the official site I linked, and when they do so, they find that the old "Format a drive to FAT32 and copy the content" does not work as painlessly for UEFI as advertised...

    Therefore, if, instead of helping people try to work with the 5 GB ISO they already downloaded, which they can most certainly do, your first approach is "Let's make you download another 4 GB of data through the MCT or elsewhere so you can use my preferred approach", you'll excuse me from not considering it as that beneficial for end users.

    One also has to wonder how long the .esd will remain below the 4 GB limit. Sure. there is some good margin today, but a few years ago, the exact same thing could be said for 'install.wim'. Then what happened is that Microsoft had no choice but to go over the 4 GB limit, first with some pre-release ISOs (I think that happened with Windows 8.1 pre-release), then for the Windows ISOs with cumulative updates, and finally with the default retail Windows ISOs.

    So, yes, the end result is that Microsoft are obviously pushing people towards the use of the MCT, so they can use install.esd based ISOs, which are pretty much designed to work as a workaround for the FAT32 issue. But, in all likelihood, this workaround is not going to last forever...

    So please understand that, while I am certainly not saying that everybody should use Rufus, and that I am more than happy to see more of the non tech-savvy crowd use the MCT or something else, because, by design, I tried to strike a balance between hand-holding and power-to-the-user (which is why I will expect the user to know and pay attention to the "Target type" for their system in Rufus rather than blindly click "START"), I don't think the absolutism you display about there not existing situations where you will need/want an application to help create Windows 10 flash drive is warranted. As such, I can't help but express concern if you see it as your duty to debunk this as a "myth", when it's difficult to see much value in such a crusade, even more so as a lot of people do prefer, or are perfectly happy to use Rufus (or any other application for that matter). In other words, when people come to you for assistance with "I have a problem using my car", you don't go around stating "Well, you're better off not using that car", especially if you can't demonstrate that there's anything wrong with said car.

    If you want to debunk something, I'd rather you debunk the myth that there's no salvation for UEFI boot unless everything resides on a FAT32 partition. And also, if you are annoyed that people might ask for help with Rufus, kindly remind them that there exists an official issue tracker as well as a FAQ.
    Last edited by Akeo; 20 Feb 2019 at 09:34.
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  6. Posts : 15,025
    Windows 10 IoT
       #16

    NavyLCDR said:
    No offense, @Akeo, but the Microsoft Media Creation Tool creates an MBR partitioned USB flash drive with a FAT32 partition marked as active on it for a reason. That reason being is that it is universally bootable on legacy BIOS systems, UEFI systems, and UEFI system in CSM mode. If the user wants only a standard Windows 10 installation USB flash drive there is absolutely no reason to create it in any other format. And the other advantage is there is no need to disable Secure Boot in UEFI if the user wants to leave it enabled.

    Also the current Windows 10 ISO files from Microsoft contain install.esd files that do fit within the 4 GB file size limit of FAT32 so your statement ,"1. The latest Windows retail ISOs contain a file that is larger than 4 GB, therefore FAT32 cannot be used as is" is erroneous.
    I'm on your side but be advised my latest My Visual Studio (MSDN) Windows 10 Consumer ISO contains an install.wim file that is 4,447,865 KB.
    I get the file size warning if I mount and try to copy that ISO to my fat32 diskpart created thumbdrive.
    My laptop is fine doing a UEFI install from an NTFS formatted thumb drive though so it was just a bit of an inconvenience for me.
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  7. Posts : 18,424
    Windows 11 Pro
       #17

    alphanumeric said:
    I'm on your side but be advised my latest My Visual Studio (MSDN) Windows 10 Consumer ISO contains an install.wim file that is 4,447,865 KB.
    I get the file size warning if I mount and try to copy that ISO to my fat32 diskpart created thumbdrive.
    My laptop is fine doing a UEFI install from an NTFS formatted thumb drive though so it was just a bit of an inconvenience for me.
    My bet is that for the standard USB flash drive provided to general public, Microsoft will keep the standard active FAT32 partition by either compressing the wim file to esd or splitting the wim file.
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  8. Posts : 29
    Windows 10 x64
       #18

    If you are interested, I know of 2 other alternatives, besides the one Rufus uses, for the >4GB issue.


    The first one, which is the most obvious and which dism will happily do, is to split the wim into 4 GB chunks that fit on FAT32.

    Of course, the big drawback with doing that on the fly is if you're trying to do so on Windows 7, since there's no native mounting for ISOs, so you first have to extract the .wim to a temporary location before you can split it, which is very wasteful both in terms of space, resources and time.


    The other one, which Microsoft seems to have designed for fairly recently (i.e.: Long after we solved that issue in Rufus) is to copy the /efi/ directory as well as /sources/boot.wim (which is much smaller than install.wim) into a FAT32 partition (0.5 to 1 GB will usually do) and then copy the rest of the image, including the > 4GB install.wim to an NTFS partition.

    If you do that, then once the pre-initialization environment is up, which is what boot.wim is all about, then the rest of the installation process is smart enough to look for content onto the other NTFS partition.

    Now, one of the drawbacks of doing that has to do with using removable media that don't have the "FIXED" attribute (the vast majority of USB Flash Drives are like this), and a not so well known restriction that all Windows OSes used to have until Windows 10 1703 (I think - or it might have been introduced later. At any rate this is a fairly recent thing that the original Windows 10 and earlier versions of Windows do not have), which prevents them from mounting 2 partitions at once from drives that aren't "FIXED".

    And since the "FIXED" attribute is a property of the hardware, rather than something you can alter, this means that, for anything but a recent version of Windows 10, that second option can be very impractical, as you can't even tell Windows "Unmount the FAT32 partition, and just mount the NTFS one" as the OS is designed to automatically mount the very first partition with a file system it recognizes.

    So that makes it tricky for Windows 7, Windows 8 and early Windows 10 users (unfortunatley, there are people who don't upgrade to featured releases, especially in the corporate world) to use that second workaround, unless they play with the partition scheme and temporarily declare the FAT32 partition as RAW...

    Plus there's the wastage of having to keep some free space for the FAT32 partition, when you could consolidate the whole thing, as Rufus does, in a single NTFS partition (again, the only wastage from Rufus is that 512 KB, yes that's kilobytes, even as it provides a separate NTFS driver for all of x86_32, x86_64, ARM and ARM64, that it adds at the very end of the drive and which even Disk Manager fail to see as anything but a zero-sized partition...), but I suppose Microsoft have never been well known for providing the most efficient solutions.

    If you google around, you should have little trouble finding tutorials on how to accomplish any of the above...
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  9. Posts : 15,025
    Windows 10 IoT
       #19

    NavyLCDR said:
    My bet is that for the standard USB flash drive provided to general public, Microsoft will keep the standard active FAT32 partition by either compressing the wim file to esd or splitting the wim file.
    I think thats a good bet. Was just pointing out that the 4+ GB install.wim is out there, from an official Microsoft source. Granted your average Joe public won't be getting it via a My Visual Studio subscription.
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  10. Posts : 15,025
    Windows 10 IoT
       #20

    The "FIXED" atribut raises it ugly head when you try to make a Windows To Go drive. Via the official built in tool. I have a nice fast Kingston Hyper X 64 GB USB 3 thumbdrive. Windows to go won't let me use it though as its not flagged as fixed, thus not an official Windows To Go certified drive. But then lets me use a slow as mollasis 5400 RPM Laptop IDE drive in a USB enclosure.
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