ZFS 2.3.1 has been officially released – by the OpenZFS team! – though, is is simply not yet included in PVE delivery.
For me personally, there's no reason not to use it. My team and I have spent about 7 man-weeks testing, migrating, and preparing repositories. While anyone could technically download the official release and compile it, we had to do this on multiple systems for our own infrastructure and for customers. That’s why we decided to invest some extra time (and money) to make prebuilt packages available for everyone – simply to make it easier to adopt.
I don’t believe stability is the issue here – support might be. That said, getting everything working properly was a lot more effort than we expected. Someone commented that “it can’t be that much work” – well, it is, if you want to do it properly ;-)
I’m not trying to push anyone to use it. All I’m saying is: it’s released – and not only includes the improvements that have been discussed, but also a lot of bug fixes, making ZFS more stable and reliable overall.
As for performance: hard to generalize. On Gen5 NVMe and under demanding workloads, we’re seeing speedups of around 1.5x to 2x. On older hardware? Likely less – we haven’t tested that in detail.
Happy to discuss more if anyone has specific questions
– M.