Recommendations for Dell R7715 Hardware selection / controller question

[jcol]

Hello all, we are configuring a Dell server for ProxMox with ZFS (no Ceph), and I wonder what I should select in terms of Controller.
Prefix: I know that ZFS is not compatible with HW RAID, and we do not want to do ZFS with HW RAID. However, on one hand, we also have loads which we want to put on an LVM (where I would like to see HW RAID in place for ease of error handling), and on the other hand, the newest generation of Dell servers cannot be configured in an HBA-only version for SAS/SATA, i.e. there is always a PERC controller in place for these disks (for NVME, you can do "direct" mode which is what I want to order). I clarified this with our Dell representative so I am pretty sure this info is accurate.

So my question boils down to: How is the practical performance experience with using a modern DELL PERC controller like the 965i offered for R7715 in "passthrough" mode for ZFS? Note that for this controller it is not possible to use alternate "HBA" firmware as far as I know, so the only thing you can do is present the disks as non-RAID disks which passes all things like e.g. SMART info, but obviously the disk is still behind the controller performance-wise.

With the previous generation R7615, you could configure a HBA-only server which is what you find in several posts on this forum, but that generation does not offer the CPUs that we want to use .....

Thank you for any input, jcol

 

[waltar]

Nvme's could be get pcie direct connected without a perc and even in a R7715.
PS: H965i is last generation pcie gen4 and H975i new pcie gen5 raid controller but in a config there is only nvme backplanes cpu direct connections or by perc between possible and not both (eg half/half).

 

[jcol]

Hello Waltar, thank you for the answer; I know that I can connect NVME directly, that is what I wrote above. But what you write then is not true; I can get a 24 backplane with 16 PERC-connected SATA/SAS ports and 8 NVME direct ports. I know a company that already has such a config. So we have no problem connecting NVME drives directly and using them for ZFS. My question is regarding the other drives behind a H965i controller (or alternatively a "simple" H365i controller). It would be great if anybody with experience with one of these controllers could share his or her mileage!