@olivierlambert will repeat on everything!

@olivierlambert Interestingly, so far I've seen about a 40% increase in write performance and IOPS from adjusting the scheduler in dom0 by adding elevator=noop as a kernel parameter and a further 10% from repeating the same on the VM.

I'm going to experiment next with migrating the disks so that the mirror is achieved in the VM with three separate pifs instead of in dom0. Then may try other more radical approaches like passthrough.

Fixed it!

Hidden bios menu Ctril-A on the DL380 seems to have sorted it. Then enabled PCI Express 64Bit BAR Support

(Playing with building a gpu enabled kubernetes cluster on XCP-NG.)