Re: How to safely switch grub booting in-place from one drive to a replacement with RAID?

[darrin . thomas]

Hi,

On Thu, Feb 23, 2017, at 07:30 AM, Andrei Borzenkov wrote:
> With /boot/grub on Linux MD you can install grub2 in MBR only. Run
> grub-install (or grub2-install depending on your distribution) twice for
> each disk
> 
> grub-install /dev/sda
> grub-install /dev/sdb

I just want to be sure I understand what you mean by 'each disk'.

Each Disk of the array?

In my case that's

  grub-install /dev/sdb
  grub-install /dev/sdc

Or do you really mean

> grub-install /dev/sda     <-------- the single, non-RAID disk     
> grub-install /dev/sdb     <-------- only ONE disk of the array

?

Oh and I just wanted to be sure about the "metadata" I can use.

I read some recent info that using RAID1 metadata == version 1.2 is OK with 
Grub2 for "/boot" partition.  IIUC it used to not be but newer versions of 
grub2 took care of that.

Is that right?

> You will also need to configure your distribution to use these locations
> by default, so it automatically writes new version of grub into correct
> location(s) during package update. How to do it is distribution-dependent.

I think that's done here on Opensuse with

/boot/grub2/device.map

> You may also want to recreate grub.cfg as well.

Yeah, that one I got! :-)

Thanks,

Darrin