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> I'm the author of EasyBCD Thank you! Also, maybe you can answer this: what's the 'correct' way for systems to handle multiple disks with an ESP partition ea

> I'm the author of EasyBCD Thank you! Also, maybe you can answer this: what's the 'correct' way for systems to handle multiple disks with an ESP partition each? In other words, if I'm using software RAID and clone the partition tables, should I assume that the UEFI firmware will default to the first disk's ESP, or is that set when boot configurations are updated?

ComputerGuru 9y ago
> Thank you! No problem! Glad you found it useful. > if I'm using software RAID and clone the partition tables, should I assume that the UEFI firmware will default to the first disk's ESP With regards to your question: I guess it depends on what you mean by "software" raid. Enabling RAID in the "BIOS" (that term has now come to encompass the firmware configuration utility for UEFI motherboards as well) (typically Intel "RST" rapid storage RAID, nvraid for nVidia chipsets (less common these days), AMD raid, etc.) is 100% software raid, which does nothing more than make the BIOS aware of its presence (and toggle a flag so that RAID drivers can find the array) so that it doesn't run into exactly the problem you describe, i.e. it'll be aware of the cloning at a level higher than the UEFI bootloader init, which will only see the virtual raid volumes rather than their independent components. Now if you put all that aside and are just wondering how it selects in the presence of multiple ESPs on different devices that made it through to the bootloader layer: the UEFI "BIOS" doesn't know (and can't know) since UEFI has done away with the concept of drive order entirely. You can set the order manually in the "boot device order" section (typically on the boot tab in the BIOS config) or choose the one-time boot target via F11 or F12 at the boot-up screen, but otherwise it's just a tossup and the BIOS is free to chose any local device's ESP as "the" ESP. In practice, it'll choose one of the SATA drives (assuming a mix of other interfaces such as NVMe), either the first to respond (not an issue with SSDs which respond quickly, but magnetic media takes time to spin up if you're still using old HDDs) or the first to be enumerated by the SATA controller (which has its _own_ firmware and its own level of abstraction and logic (and bugs) and whatnot). BUT in the case of software raid, that RAID 0 should actually extend to the GPT itself and both drives will have the same content and mirrored ESPs, so in practice it won't matter which is loaded (so long as your OS doesn't do anything stupid like try to modify the on-disk structure before loading the RAID-aware storage driver. I've seen BIOSes that "helpfully" store a copy of the current firmware to a locally-attached disk with an understandable partition format (so FAT32) that ended up breaking a RAID because the drives were no longer in sync because the BIOS wasn't aware of the mirror).

ComputerGuru 9y ago

> Thank you! No problem! Glad you found it useful. > if I'm using software RAID and clone the partition tables, should I assume that the UEFI firmware will default to the first disk's ESP With regards to your question: I guess it depends on what you mean by "software" raid. Enabling RAID in the "BIOS" (that term has now come to encompass the firmware configuration utility for UEFI motherboards as well) (typically Intel "RST" rapid storage RAID, nvraid for nVidia chipsets (less common these days), AMD raid, etc.) is 100% software raid, which does nothing more than make the BIOS aware of its presence (and toggle a flag so that RAID drivers can find the array) so that it doesn't run into exactly the problem you describe, i.e. it'll be aware of the cloning at a level higher than the UEFI bootloader init, which will only see the virtual raid volumes rather than their independent components. Now if you put all that aside and are just wondering how it selects in the presence of multiple ESPs on different devices that made it through to the bootloader layer: the UEFI "BIOS" doesn't know (and can't know) since UEFI has done away with the concept of drive order entirely. You can set the order manually in the "boot device order" section (typically on the boot tab in the BIOS config) or choose the one-time boot target via F11 or F12 at the boot-up screen, but otherwise it's just a tossup and the BIOS is free to chose any local device's ESP as "the" ESP. In practice, it'll choose one of the SATA drives (assuming a mix of other interfaces such as NVMe), either the first to respond (not an issue with SSDs which respond quickly, but magnetic media takes time to spin up if you're still using old HDDs) or the first to be enumerated by the SATA controller (which has its _own_ firmware and its own level of abstraction and logic (and bugs) and whatnot). BUT in the case of software raid, that RAID 0 should actually extend to the GPT itself and both drives will have the same content and mirrored ESPs, so in practice it won't matter which is loaded (so long as your OS doesn't do anything stupid like try to modify the on-disk structure before loading the RAID-aware storage driver. I've seen BIOSes that "helpfully" store a copy of the current firmware to a locally-attached disk with an understandable partition format (so FAT32) that ended up breaking a RAID because the drives were no longer in sync because the BIOS wasn't aware of the mirror).