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
> and its md driver, and therefore can't be reading the partition
> _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
> that a file system doesn't care if the block device it's in actually
> 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
> (manually or automatically) maintain a backup /boot partition on the
> 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
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