m.2 riser card pcie for 4x slot with 2x Intel Optane 800p.

[Spoon]

I'm trying to figure out the best setup for special metadata vdev and was wondering if it was possible to use a dual M.2 riser in a 4x PCIe slot (8x physical) with 2x Intel Optane 800p 118GB NVMe drives. The drives are x2 electrical and the slot would be bifurcated 2x/2x. Does anyone know of a riser card that would fit the bill?

Machine is a HP ML30 Gen10. Dataset has a file size distribution as follows:

 

[Etorix]

Bifurcation is a matter for the motherboard. If your BIOS does not have an option to bifurcate this x4 slot into x2x2, then it's not possible. Or it would require a riser card with a PLX chip—and likely come up more expensive than the two Optane drives.

The easiest option is to put these two drives in two x4 slots, and live with the wasted lanes (that's a built-in feature of x2 devices really).
If you don't have two slots to make a mirrorred special vdev, as it should, an alternative could be to use a single Optane drive as a metadata-only persistent L2ARC. If the workload reads metadata more than it writes to it, this may give most of the expected benefits.

 

[Spoon]

I hadn’t considered a persistent L2ARC for metadata (or knew it existed ), I’ll have a look into how that is setup. Thanks