On Tue, 24 Feb 2009 15:21:23 -0500 "Barclay, Daniel" <dan...@fgm.com> 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? > >> > > > > 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? > > > > >> ... 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). > > > > Daniel Hi, Daniel et al The following is an outline of my setup on a couple of the system disks. Roughly I have two md devices for the host system, md0 & md1: j...@host:~$ df -m Filesystem 1M-blocks Used Available Use% Mounted on /dev/md0 9389 7157 1755 81% / tmpfs 4005 1 4005 1% /lib/init/rw udev 10 1 10 2% /dev tmpfs 4005 0 4005 0% /dev/shm /dev/dm-0 40318 11628 26642 31% /home /dev/dm-4 19686 15356 3331 83% /home/jack/XP_VDI /dev/dm-6 30238 7453 21250 26% /home/jack/suse /dev/dm-2 3024 70 2802 3% /tmp /dev/dm-1 8064 3426 4229 45% /var /dev/hda 90 90 0 100% /media/cdrom0 The only concern I have is that / is marginally small. It's expandable tho. /boot is just on /mdo. I have run without incident for over a year. Provides sufficient isolation from my bumbling around... 8-) FWIW. Jack . -- -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
