Re: how does GRUB read from /boot on software-RAID partition?
Barclay, Daniel wrote:
> Some articles about GRUB and md-based RAID1 (mirroring) seem to imply
> that GRUB
>
> can read files (including the kernel and the initrd file) from /boot
> on the
> filesystem on a mirrored partition.
>
I never tried, but I've seen several reports that it works.
>
> Since GRUB hasn't loaded the kernel file yet, GRUB can't be using the
> kernel
> and its md driver, and therefore can't be reading the partition
> _as_a_RAID_
> _volume_ (/dev/mdX), right?
>
>
> So is GRUB just reading the partition directly to get to the file system?
>
GRUB does not know anything about RAID, so I assume this is true.
> Specifically, is GRUB taking advantage of the fact that the RAID
> metadata is
> written at the end of a partition that is a component of a RAID volume
> (and
> that a file system doesn't care if the block device it's in actually
> contains
> more blocks than the filesystem knows about)?
>
I'd suppose so.
> If so, how reliable is that?
>
> Should one put /boot on a plain, non-RAID partition on one disk and
> somehow
> (manually or automatically) maintain a backup /boot partition on the
> second
> disk, or is it fine to put /boot on a mirrored partition (so maintaining
> redundancy is automatic) and let GRUB read the partition directly?
>
Again, while I haven't tried, I've seen several reports that this works.
(Don't forget to install GRUB on both disks, should one fail.) So why
make things more complicated and not automatic?
--
You know what they say -- the sweetest word in the English language is revenge.
-- Peter Beard
Eduardo M KALINOWSKI
eduardo@kalinowski.com.br
http://move.to/hpkb
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