Hi, I have found, that my problem is caused only in case of mdraid device partitioning. To reproduce: 1. Take 2 HDD (at least by 50 GB) 2. Run from any LiveCD 3. Make two partitions on each HDD: for 256-1024MB and for remaining space, make first partition bootable 4. Create mdraid1 around second partitions of both HDD 5. Repartition md device by 3 partitions: 10GB (md0p1), 20GB (md0p2) and remaining space (md0p3) 6. Using cryptsetup configure luks encryption over md0p2. 7. Install debian 9 or 10, using: /dev/sda1 - /boot, /dev/md0p1 - /root, /dev/md0p2 - /var, /dev/mapper/<crypt-device> - /home After reboot system do not start if default boot options are specified. It will wait for some devices to be ready, but no any password prompt. There is only one way to boot system: run rescue mode and then exit from rescue shell using Ctrl-D.
If you create on HDDs four partitions and use them to build four RAID1 devices, then encrypted device configured on /dev/md3 will start on boot successfully (after prompting password). So I think, some boot scripts/services does not know anything about md device partitioning.