Booting from drive located on a M.2 PCIe Adapter Card

You can't boot from a drive if the BIOS isn't aware of it. So the card would need a boot rom. If there isn't then you can't boot from it.
 
i.am.the.problem said:
Has anyone tried booting from a drive located on a M.2 PCIe Adapter Card?
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As previously mentioned this is a very vague question - but here's my answer: Yes, I do that on several (many) systems successfully.

Note that "M.2 PCIe" adapters come in many different "flavours". You have simple physical adapters. In such a case, the system will "see" this device as a regular PCIe device. Therefore, you can only boot from that if your system (i.e. BIOS/EFI) supports that.
Other adapters have on-board controllers which allow you to use non-PCIe M.2 storage devices on your PCIe slot. Notably these includes PCIe adapters with SATA controllers so you can use m.2 SATA SSDs. In that case the system "sees" a SATA controller with the corresponding SATA drive(s) connected to that.
 
If we assume an NVMe drive on a M.2 adapter then yes you can boot from the device.
But...
Some of this depends on the machine. It also depends on the mode you run the machine.
For example most SuperMicro X9 (Sandy/Ivy Bridge) series boards can only boot NVMe in EFI mode.
 
On a slim-PC HP Prodesk Gen2 the machine will only boot from an NVMe with an Option ROM.
This limits it to consumer class NVMe like Samsung 970 and Toshiba XG5.
Most server grade NVMe don't use Option ROM.
Option ROM is used in legacy bios mode.
 
Phishfry said:
You do realize that this is a vague question? What kind of drive? SATA or NVMe?
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Shouldn't make a difference. If you can see the drive in BIOS as 'Storage', it should be able to boot. Good motherboards like Asus or Gigabyte (I have both) should be able to see storage devices on either connection.
 
Haven't tried on a Dell (I think they call them BOSS cards?), but Startech and Supermicro x1 and x2 M.2 NVME cards have worked with the Supermicro servers I've tried them with, and FreeBSD not had any trouble finding the nvd0/nvd1 devices.

If you have a card that supports more than one M.2 NVME then you have to set the bifurcation in the BIOS.
 
i.am.the.problem said:
I'm hoping to use one of these M.2 PCIE adapter cards:

https://www.scan.co.uk/products/gig...ie-30-x16-low-profile-adaptor-card-2280-22110

[...]
In a DELL R540 server purchased about a year ago.
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That adapter card also needs PCIe bifurcation support by the BIOS/UEFI. Dell has (had) some strange policies about that and doesn't support it on all systems.
If your board/BIOS doesn't have bifurcation support, you need an adapter card with a PCIe switch chipset (no retimer chipset!) - those are at ~twice the price of that simple carrier card.
IIRC PCIe gen 4 specifically requires bifurcation support in the standard (and all chipsets/CPUs support in anyways), but especially on desktop hardware this gets ignored _a lot_ by the vendors and the BIOS options are only made available on their high-end boards with a hefty price tag...

If you only need 2 M.2 sockets, these cards are also available from supermicro at very decent prices. I've deployed 4 or 5 of their 2-port variant [1] which costs ~40-50EUR here in germany. Supermicro also offers a wide range of other M.2/NVMe adapters, some with PCIe switch. [2]
Of course those cards also work on non-supermicro systems. I've used them on dell and asus boards as well - in the end they are just standard PCIe cards, not proprietary add-on cards.

I'm also not sure about the space requirements of that gigabite card - adding drives to the back of the card would require a free adjacent PCIe slot as those drives would protrude into that space. I highly doubt this is standards-conformant in any way (just like NVMe drives with huge aluminium coolers)


[1] https://www.supermicro.com/en/products/accessories/addon/AOC-SLG3-2M2.php
[2] https://www.supermicro.com/en/products/storage/cards
 
sko said:
I'm also not sure about the space requirements of that gigabite card - adding drives to the back of the card would require a free adjacent PCIe slot as those drives would protrude into that space. I highly doubt this is standards-conformant in any way (just like NVMe drives with huge aluminium coolers)
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Those cards are about the same size as a dGPU (Think RX 550 or a GTX 1050), and they fit into the same slot. If you don't think you can fit something like that into the spot you want for the card, then you'll know the card is not gonna work out, either.
 
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