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Will Roberts avatar Server

Properly Configuring Grub for a Two-drive raid1 to Support Boot After a Drive Failure

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Will Roberts

Edit:

So, I think the question still applies below, but I realized that the system is actually booting on the second drive, it's just missing /home, /boot and /etc/fstab. I am sure there is more missing, but I guess the better question now is;

How do you properly boot a system with a failed drive on software raid1 and/or is there any configuration requirements to get this working properly? Is this even possible?

I verified that the uuid for /boot (which is on /dev/md126) matches across both drives (which are /dev/sda6 and /dev/sdb6).

I am trying to install Centos 7 on a 2-drive software raid1 setup. I'd like to install grub on both drives so that if one fails, the system will still boot.

I have /boot, /home, /var and / are all different partitions. I think the important thing to note is that /boot is it's own partition and it is ext3.

After installation I install grub to both devices with:

grub2-install /dev/sda
grub2-install /dev/sdb

and redo the grub.cfg

grub2-mkconfig -o /boot/grub2/grub.cfg

Grub appears to be using UUID and not hd0,0 by default.

When I pull one drive and boot, the system gets past the grub, tries to start Gnome, but about about 2 minutes, the system drops from the GDM loading screen to a shell with a few errors; One thing of note though is that /home and /boot don't exist. /etc/fstab doesn't exist either. The shell complains about a uuid mount point not being found either.

I'm not sure what else is required, but I would like the system to still boot with one of the two drives from the raid1.

references:
https://newbedev.com/how-to-correctly-install-grub-on-a-soft-raid-1 https://unix.stackexchange.com/questions/230349/how-to-correctly-install-grub-on-a-soft-raid-1

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Michael Hampton avatar
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Michael Hampton
Eh? The CentOS installer should have set this up for you.
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Will Roberts avatar
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Will Roberts
From what I see, the installer install grub to either sda or sdb but not both. It's the option on the bottom of the first screen for drive selection / installation location. I cannot check both.
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Michael Hampton avatar
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Michael Hampton
You didn't change the type to RAID.
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Will Roberts avatar
gf flag
Will Roberts
It is set to raid, raid1 and i also ensured both drives were highlighted. I am trying the install again. This issue isn't the boot actually... thinking about it last night, the system actually boots and gets past grub... all the way to GDM... then it drops to terminal (after X started, but before being prompted to log in). /home and /boot are missing and so is /etc/fstab. I think the issue lies somewhere else. I just don't know where... and why the system booted with only portions mounted.
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