I'm testing mdadm RAID1. I'm using two HDD. Created / (/dev/md0 with /dev/sda1 and /dev/sdb1) and swap (/dev/md1 with /dev/sda5 and /dev/sdb5) After OS installed. I removed one HDD and reboot the system. The system show black screen (after GRUB boot loader loaded). I need to force shutdown the system and restart again. Then the system can boot into OS. I tried several times. It's all the same. I need to reboot twice. Is that normal?
There are 2 aspects to your issue:
- When you create the RAID you are eventually asked if you want to boot in degraded mode. I suppose you answered with yes
- Even when boot degraded is enabled it takes some time - I had the same feeling you had just now but was more patient it seems :-), so please wait a while (the system appears to not do anything at all - I suppose it is waiting for the second drive to "wake up").