On Tue, Feb 24, 2009 at 03:21:23PM -0500, Barclay, Daniel wrote: > Eduardo M KALINOWSKI wrote: > > Barclay, Daniel wrote: > ... > >> 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? AFAIK > >> > > > > GRUB does not know anything about RAID, so I assume this is true. > > That's what I have been thinking, but I just found the message at > http://www.mail-archive.com/linux-r...@vger.kernel.org/msg09712.html > that says:: > > ... once grub2 has determined that the intended boot partition is > a raid partition, the raid code takes over ... and it scans for all > the other members of the raid array and utilizes whichever drives it > needs to in order to complete the boot process. ... [I]t doesn't > need any member of a raid1 array to be perfect[;] it will attempt a > round robin read on all the sectors and only fail if all drives return > an error for a given read. > > Is that _just_ for GRUB2 and or does the current GRUB (0.97) in Lenny > also do that? > AFAIK only GRUB2 can do the round-robin thingy. GRUB goes after the one disk it knows about.
> > >> ... is GRUB taking advantage of the fact that the RAID metadata is > >> written at the end of a partition ... > ... > >> 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. > > ... So why make things more complicated and not automatic? > > I don't get why you're asking that. I _am_ trying to avoid the complicated > and non-automatic solution (trying to check whether the simpler solution is > reliable). I had a box with two SATA drives. I had three partitions on each drive, each drive partitioned identically. First partition was for raid1 for /boot, second partition was for raid1 for LVM, third partition was for LVM alone. This was with Etch, installed directly with the installer. /boot on raid1. Installed grub on both disks. Since the remainder of the system was on LVM over raid1, the dev-mapper took care of device names. I tested booting by unplugging (power and data) each drive in turn, booting with grub was never a problem. Doug. -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org