Creating a Macrium Reflect USB boot media

Without knowing what system model you have, not possible to answer.   If it's in UEFI mode, that's what you need for boot media -- and you'll need to press F12 to boot from it when you power up the system.

Actually, the option in Reflect's Create Rescue Media wizard is to create either legacy or "multi-boot" media, not UEFI-only.  The only difference that checkbox makes is that when it's enabled, Reflect will only create Rescue Media on a flash drive formatted as FAT32.  When it's disabled, Reflect will create Rescue Media on a flash drive that's formatted either FAT32 or NTFS.  The underlying issue is that for reasons not worth getting into here, Legacy systems boot just fine from either FAT32 or NTFS partitions.  But with UEFI systems the system firmware has to natively support reading the file system of the partition being booted, and in the UEFI spec, FAT32 support is mandatory, but NTFS support is optional and not very widely implemented -- and therefore it's not a good idea to use NTFS if you're trying to create media that can be booted in UEFI mode.

If your XPS system is normally configured to boot in UEFI mode, then as long as you have a flash drive formatted as FAT32 and check the multi-boot box in the Rescue Media wizard, you'll be able to boot the Rescue Media in UEFI mode, no need to switch the system to Legacy.  The easiest way to do that is to press the F12 key during system startup to access the one-time boot menu.  As long as the flash drive was inserted when the system first started up, you should see it listed as a boot option, and then you don't need to mess with the BIOS boot order.  And incidentally, you specifically would NOT want to temporarily switch to Legacy anyway, because the Rescue Media's "Fix Boot Problems" function operates differently based on how the Rescue Media was booted.  If it was booted in Legacy mode, it attempts boot fixes meant for Legacy systems, so if your system normally boots its OS in UEFI mode and you temporarily set the system to Legacy just to boot your Rescue Media, then the Fix Boot Problems function would be useless.

OK thanks a lot! This should really clear up creating USB rescue media and how to use it for myself and many others who have just purchased an XPS :Yes:.

@jphughan​ 

FAT32 is only good if your ISOs are smaller as in Under 4Gb.  when creating a Macrium Reflect boot disk, formatting it as NTFS instead of FAT32 is recommended for larger image files, as FAT32 has a 4GB file size limit. NTFS allows for larger image files and avoids the need to split the image into multiple parts

@RAJ54​ , unfortunately that isn’t the whole story at all. You are correct that FAT32 doesn’t support files larger than 4 GB. So if you only need to boot a PC in Legacy BIOS mode, NTFS is the preferable option. However, PCs for over a decade now have supported booting in UEFI mode, and some PCs these days ONLY support UEFI mode. And UEFI PCs expect to boot from FAT32 partitions because that support is mandatory in the UEFI spec. By comparison, support for booting directly from NTFS is optional in the UEFI spec and therefore is not widely supported. And exFAT isn’t supported for booting at all.

If you look at the Windows disk of a system booting in UEFI mode, you will find a hidden FAT32 partition that operates as the bootloader partition, which then turns around and loads Windows from the main NTFS partition (C drive). That’s the main reason that partition exists.

You might also notice if you ever use the Microsoft Media Creation Tool to build Windows install media, it will be formatted as FAT32 for this reason.

As for Macrium Reflect, its Rescue Media Builder has an “Enable multi-boot” option. If you disable that, it will only focus on Legacy BIOS support and will therefore allow FAT32 or NTFS partitions as targets. But if you enable that option to ensure UEFO boot supports, Rescue Media Builder will only allow FAT32 targets.

The popular bootable media creation utility Rufus has another way around this. It allows using NTFS for UEFI booting by Rufus also creating a small hidden FAT partition on the flash drive, which contains a UEFI driver to read NTFS file systems, which then boots from the main NTFS partition on the drive. But that is an advanced build option, and it also requires disabling UEFI Secure Boot before booting from the resulting drive, since that NTFS driver is not signed by Microsoft.

Lastly, in the specific case of Macrium Refldct since that is the topic of this thread, its ISOs are never anywhere close to 4 GB in the first place. They’re around 1 GB depending on WinPE/RE version and how many supplemental drivers you add.