This is an old revision of the document!
Only for VM storage or databases do you need or want to enable sync.
It's much faster than OmniOS with OpenZFS.
It's crazy not to unless you don't have NVMe or PCIe slot!
http://napp-it.org/doc/downloads/optane_slog_pool_performane.pdf
PCIe 3.0 x8 low-profile card
Mount two M.2 800P as mirrored SLOG:
https://www.supermicro.nl/products/accessories/addon/AOC-SLG3-2M2.cfm