I see one main use case for realtime dedup (ZFS does realtime dedup). This is where you backup a greater amount of VMs ex a VEEAM backup target. In such a case dedup rates can be big enough to consider dedup instead of more disks. The main problem of realtime dedup is the huge RAM need (depending on data and recsize up to 5GB per TB dedup data) and the need to always offer enough RAM. Never try to open such a pool on a small system with less RAM. As you need RAM for performance, dedup RAM need is additional.
For such a use case, you can now use a special vdev instead of RAM to overcome the RAM problem. As such a vdev must be fast ex a mirror of Intel Optane, this is not a home solution but can be a solid datacenter solution.
For such a use case, you can now use a special vdev instead of RAM to overcome the RAM problem. As such a vdev must be fast ex a mirror of Intel Optane, this is not a home solution but can be a solid datacenter solution.