DVA3221 - HBA Drive and OS booting time

[Guich590]

Hello Everyone and thank for reading me,

I have a small issue with my new configuration, here is the specs :

Asus z390 tuf gaming plus wifi
I7-9700KF
32GB of RAM
Nvidia Quadro P200
HBA card for SAS drives OEM 9211-8i
6 x 10TB SAS Hard Drives and 2 x 4TB SAS SSD
For the OS part, I do use :
TCRP 10
Model DVA3221 (for the native integration of the Nvidia Library to use Plex with the P200)
Version 7.1.1-49652 u1 (to migrate from my real DS1515+ with synology assistant, the need to be on the same version)

The loader build and first boot all come well, successfully installing and configuring my raid groups (1 x SHR2 with the 10TB drives and 1 x SHR with the 4TB SSD, I'm using SHR because I might add some larger disk).

The issue is happening after a reboot (or a boot after a halt) with this behaviour: 
The system is booting before the hard drives (or SSD), so the synology seems to be ready but in fact it has some missing hard drives that shows up after a short delay (between 10 and 30 seconds) so all the raid groups are degraded and volumes offline...

I didn't find anyone else having this issue here.

Any guess on what might be the problem ? Is there any solution to "slower" the system boot ? (I tried extend BIOS wait time to the maximum 10 sec instead of 2 and grub.cfg timeout without any change)

Thanks for the help.