[sliken]

> Really? You somehow can't create a ZFS file system on an hardware RAID block device?

Sure you can do it, have two layers of checksums and a volume manager on top of a volume manager. But ZFS is designed to talk directly to block devices and try to detect and complain about the numerous failure modes. Like say a parity calc that goes awry because of a memory error.

For this and other reasons it's recommended that even with Hardware RAID it's recommended to configure it in JBOD mode.

I've also seen numerous cases where software RAID on top of hardware RAID running in JBOD mode is faster than just using hardware RAID.

> When you operate like that you can accommodate sophisticated integration such as this for efficiency gains.

Sure, if there are efficiency gains. If the strong bottleneck for writing to the controller is your limiting factor you might get a 33% increase in I/O. But for that to be true you need:

  * The bottleneck not to be elsewhere
  * The controller inside a NVMe device (often passively cooled) to be faster than the one on the CPU
  * The bandwidth between the PCI controller or PCIe switch and the NVMe controller to not care about a 2x increase in needed bandwidth

Seems unlikely to me.