CentOS 7: GPT and software RAID 1 without 'biosboot' partition

HTF asked:

I have a CentOS 6 server with software RAID1 (2x3TB):

– sda

# parted /dev/sda unit s print
Model: ATA TOSHIBA DT01ACA3 (scsi)
Disk /dev/sda: 5860533168s
Sector size (logical/physical): 512B/4096B
Partition Table: gpt

Number  Start     End          Size         File system  Name  Flags
 1      2048s     1026047s     1024000s     ext4               boot
 2      1026048s  5860532223s  5859506176s                     raid

– sdb

# parted /dev/sdb unit s print
Model: ATA TOSHIBA DT01ACA3 (scsi)
Disk /dev/sdb: 5860533168s
Sector size (logical/physical): 512B/4096B
Partition Table: gpt

Number  Start     End          Size         File system  Name  Flags
 1      2048s     1026047s     1024000s     ext4               boot
 2      1026048s  5860532223s  5859506176s                     raid

– md[0-1]

# cat /proc/mdstat 
Personalities : [raid1] 
md0 : active raid1 sdb1[1] sda1[0]
      511936 blocks super 1.0 [2/2] [UU]

md1 : active raid1 sdb2[1] sda2[0]
      2929621824 blocks super 1.1 [2/2] [UU]
      bitmap: 1/22 pages [4KB], 65536KB chunk

unused devices: <none>
  • md0 is mounted on /boot
  • md1 is used for physical volume with ‘root’ and ‘swap’ logical volumes

I would like to use the same partitioning layout on CentOS 7 however anaconda is complaining about missing ‘biosboot’ partition:

Your BIOS-based system needs a special partition to boot from a GPT
disk lable. To continue, please create a 1MB ‘biosboot’ type
partition.

Is there a way to aviod this? I was thinking to create a two separate ‘biosboot’ partitions on each disk to mirror both HDDs.

My answer:


Creating a BIOS boot partition on each disk would be fine. If you used automatic partitioning, this is what would happen anyway.

You can (and probably should) also boot the installation with UEFI rather than legacy boot, and a BIOS boot partition is not needed in this case (but you will need an EFI partition).


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