3

in a two disk setup

/dev/sda
/dev/sdb

i created per disk 3 partitions

bios_grub   1mb
linux raid  512mb   md0 (/boot - ext3)
linux raid  rest    md1 (physical volume for lvm)

the answer on https://unix.stackexchange.com/a/218384 states that it is not possible to create a mirror raid for bios grub

You will need hardware RAID if you want the BIOS boot partition to be mirrored.

but on https://askubuntu.com/a/57010 it looks like it is possible but there is no info how it works

You will need hardware RAID if you want the BIOS boot partition to be mirrored. You can, however, install GRUB to multiple drives; just run grub-install in the target OS on each drive that has a BIOS boot partition (give it the entire drive, like /dev/sda, as an argument; grub-install will figure out the location of the BIOS boot partition from the GPT).

so is it possible to create a software raid for the bios_grub partition? if yes how? currently i use fai setup-storage to create the partitions.

1

Originally I used this post to get my installation done. But I was not able to install the mbr on the raid of the boot partitions. The process terminated every time and I did it several.

There is another thread which was interesting for this issue, but also not the winning solution.

To get the installation working I just skipped the raid-ing of my boot partition on sda, but nevertheless created an additional boot partition on my sdb. Both hdds have a size of 4TB with GPT. After the installation has finished, I used grub to install the bootloader on sdb's boot partition, too.

Also many of the tuts around (including the first link in this post) want you to flag your boot partition as bootable. That did not work with any of my tries.

Maybe this will give you some inspiration with you ongoing.

  • The post you refer to is clearly about setting up software RAID on traditional MBR-partitioned disks. Using GPT-partitioned disks with a special BIOS boot partition is going to be different. Also, when installing GRUB on the second half of the RAIDed disks, you must ensure that it will only use the disk it's located on, no matter whether the first disk exists or not: when you need to boot from the second software-RAID disk, it usually means the first one is either failing or already dead! – telcoM Mar 6 '18 at 7:28

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