Is there a way to keep DDT out of ram?

TrueNAS General
1

I got a deal on some sizable Optane drives.

Given the super low latency of Optane, I figured there might be a way of keeping the DDT out of ram.

Is there a setting in openzfs to allow this.

2

This is what a dedup vdev (or more generally a special vdev) is for. Mind that this is pool critical and require redundancy.
Else, if you have enough RAM, you may also use Optane as L2ARC for metadata. Redundancy is not required in this case.

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