Hi xoxo!
I can't give too much input to this topic now but I can say few things which I met for last few months. Generally I switched to Arch because sometimes I game on VM with Windows and I need more actual versions of qemu, virt-manager and libvirt. I found that Arch has quite recent versions of those. Of course I could compile binaries by myself under Debian but I'm not so good at that. I think Debian is still a great distro. So... Once I performed performed some test on my second machine with two ADATA SU800 128 Gigs SSDs in RAID 0 with mdadm. IRST was disabled in UEFI. I tested speeds with Gnome-disks (Gnome-disk-utility package) and speeds were about 1GB/s for writes and reads using 1GB sample size. I know it's not the best testing utility and results from other software may be quite different but speeds were good - that's why I think mdadm does good job independently from IRST. Also I tested two NVMes in my main PC in RAID 0 with mdadm. IRST was disabled here too. My all partitions are aligned to 4096 bytes. For chunk=512KB I got these results:
- Gnome-disks: reads: 6,7 GB/s , writes: 1,2 GB/s (1GB sample)
- dd (I found these methods here:
https://askubuntu.com/questions/87035/h ... erformance ):
$ time sh -c "dd if=/dev/zero of=testfile bs=1G count=1 && sync" - gives writes ~ 1,3 GB/s
$ echo 3 > /proc/sys/vm/drop_caches
$ time sh -c "dd if=testfile of=/dev/null bs=1G count=1 && sync" - gives reads ~ 3,55 GB/s
As for me these speeds should be doubled for reads and quadrupled for writes (as one Samsung 960 Pro 512GB can perform about 3,5 GB/s in reads and 2,1 GB/s in writes) but I think NVMe technology is still too new or maybe NVMe drivers for Linux aren't good enough now.
I'm not sure now (50/50 - as I've tried many setups on my PCs since few months) but I think I succeded with IRST and NVMes under Arch (with dmraid - not mdadm). One thing that I'm sure of is that I had to stop mdadm service to make dmraid work properly and discover IRST's RAID 0. However I can't test any of these things now because I don't want to destroy my current system. Also I think I couldn't make IRST and mdadm work together as I would probably be using it now.
I hope this can help you somehow.