Comment by throwaway2048

NetBSD ZFS has rather severe bugs, was this addressed by bitrig? They have remained unfixed in NetBSD for quite some years now.

    Known Bugs
    
        vnode reclaiming deadlocks
        vnode fsync bug
        kmem_cache_alloc/ aka pool_cache_get panics

https://wiki.netbsd.org/users/haad/porting_zfs/

Should also be noted that dtrace and zfs can never be actually integrated into OpenBSD due to them refusing to import CDDL licensed code.