Hardware question about PCIE NVME expansion cards

TrueNAS General
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Greetings,

I have a PCIE NVME expansion card which has two slots: one for NVME and one for SATA drives. I have purchased the card when I found out that when I install NVME directly on the m2 slot of the motherboard, it will turn off some of the lanes responsible for the SATA ports. TrueNAS won’t see the disks anymore.

Card info: PCEM2-DC PCIe NVMe+SATA M.2 adapter | Axagon
Motherboard info: ASRock > Z270 Extreme4

The expansion card currently has a single NVME disk installed on it. Question is: Would installing a second SATA disk on it cause more lanes to be dedicated to the card and taken from other motherboard periphery? Like taking some of the lanes dedicated to the SATA or PCIE lanes?

The motherboard has just three PCIE lanes, two of which are already occupied with the NVME expansion card and Interl i350 NIC. I plan on purchasing my first HBA card in the upcoming months, as I will need more disks than now. Meaning I will occupy all 3 PCIE lanes available on the motherboard.

I want to know whether I am pushing the boundaries of this motherboard, or I can yeet another M2 SATA disk on the card, since I wish to mirror my TrueNAS boot image, since I had a bad experience of my previous NVME dying. I know backing up my config can save me from disasters (and I’m doing it) but I simply wish to avoid downtime because of another corrupted NVME.

Thanks.

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Hey @scotrod

I have a similar card - the short answer here is “no” because the SATA M.2 slot only takes power from the motherboard/add-in-card - there’s no data path. You still need to connect the standard SATA 7-pin port to an open (and active) port on your motherboard or controller with a short cable.

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Thanks for the answer! I totally forgot that there’s a SATA port on the expansion card as well, which suggest this. Completely went over my head.

I guess I have a third question - would it be a problem for TrueNAS if its boot image is located on two disks, only one of which is NVME?

If I am to find another way of making a mirrored boot, is it fine if I just replicate it to a M2 SATA disk and NVME, instead of two of the same type of disks? I am aware that speed will be throttled according to the slower disk. I just want to be aware whether TrueNAS would be having a ‘word’ against this.

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Nope, it shouldn’t care about that, and it sounds like you’re fully aware of the limitations of mixing media types here - although I doubt you’ll notice any measurable differences.

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I know it’s already answered, but I pulled out the relevant quote from the linked page

SATA connector to connect the motherboard when a SATA M.2 SSD is used.

Ie, the card just extracts the sata signal from the sata m.2

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