Greetings –

Ok, I have my CentOS 7 KVM host system installed and I want to be able to boot the system from either installed drive if one of them fails. My objective is to have the following layout for the two 3 TB disks.

sda1 /boot/efi sda2 /boot sda3 RAID1 with sdb3

sdb1 /boot/efi sdb2 /boot sdb3 RAID1 with sda3

The system is installed and boots from sda[1,2] and md127 (sda3 and sdb3). sdb[1,2] were untouched during the installation, and had been partitioned as FAT32 prior to the installation exactly the same as sda[1,2] using GParted. A GPT partition table was added to both disks before partitioning. The current partition information for my two drives is:

Disk /dev/sda: 5860533168 sectors, 2.7 TiB
Logical sector size: 512 bytes Disk identifier (GUID): 0C26A36C-3857-4E97-85CC-2D4E57F4015A
Partition table holds up to 128 entries First usable sector is 34, last usable sector is 5860533134
Partitions will be aligned on 2048-sector boundaries Total free space is 2925 sectors (1.4 MiB)
Number Start (sector) End (sector) Size Code Name
1 2048 1026047 500.0 MiB EF00 EFI System Partition
2 1026048 2050047 500.0 MiB 0700
3 2050048 5860532223 2.7 TiB FD00

Disk /dev/sdb: 5860533168 sectors, 2.7 TiB
Logical sector size: 512 bytes Disk identifier (GUID): A3F0F6C1-A395-4A24-8940-BDE803E5D073
Partition table holds up to 128 entries First usable sector is 34, last usable sector is 5860533134
Partitions will be aligned on 2048-sector boundaries Total free space is 2925 sectors (1.4 MiB)
Number Start (sector) End (sector) Size Code Name
1 2048 1026047 500.0 MiB 0700
2 1026048 2050047 500.0 MiB 0700
3 2050048 5860532223 2.7 TiB FD00

sda1 and sda2 were reformatted during installation; with sda1 showing in GParted now as FAT16 and a boot flag, and sda2 showing as XFS without a boot flag. sdb[1,2] still show as FAT32 and have no files on them.

What is the simplest and least error-prone way to make my second drive (sdb)
bootable if the first drive (sda) were to fail? I have done a lot of Googling over the last few days to try and understand what needs to be done, and almost everything I find is outdated in that it does not reference using grub2, and does not reference UEFI booting. I am open to reading more how-to’s if someone knows of a good one that I may have missed in the 50
plus guides I have looked at. I suspect that this is really not that difficult, but the detail that I need seems to be missing in what I have read.

Any responses may cc me directly as I only get the daily digest. Thanks.

Jeff Boyce Meridian Environmental