Some do actually like non-standard hardware and software setups. If we build a 16 TB RAID 5 (9x 2TB), can we then install Windows on it? Probably yes, with some U/EFI trickery, but then troubleshooting this contraption if hardware ever dies would be a nightmare with 9 drives. Now another try We have a leftover of drives, like all sorts of 160GB to 2TB Parallel ATA, all sorts of Serial ATA, five RAID/HBA controllers, and a motherboard. We thought of putting it all together and deploying ZFS over it. Do you think it is a good idea? Actually, no. The complexity of the failure modes for the proposed design is just mind-boggling. First of all, when ZFS crashes, there is no reliable data recovery for it. Then, multiple HBA/RAID cards from different vendors in the same system are not going to work stable. More then, with a different size drives, no common RAID scheme can be applied. Should the RAID fail, the system is not recoverable. OK you can go with ZFS hybrid filesystem-RAID capability, ...