Is that still the case? I have set up my system this way (similar to what "Super Jamie" described) but I could swear I saw the CentOS 7 installer create /boot/efi on a RAID 1 partition.You can't do this. The EFI specification mandates that the firmware recognise a FAT32 partition as the EFI System Partition. The firmware cannot recognise Linux Software RAID as an EFI System Partition.
The correct way is to install your /boot and / and other filesystems on software RAID, and to duplicate the FAT32 partition in sda1 onto sdb1, then create another EFI firmware boot menu entry pointing to the backup partition.
As far as I understand /boot/efi gets a very specific GPT GUID code of C12A7328-F81F-11D2-BA4B-00A0C93EC93B.
Can anyone confirm that my "knowledge" about this is still up to date?
Thanks in advance!