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Re: how does GRUB read from /boot on software-RAID partition?



Title: Re: how does GRUB read from /boot on software-RAID partition?

Jack Schneider wrote:
> On Tue, 24 Feb 2009 15:21:23 -0500
> "Barclay, Daniel" <daniel@fgm.com> wrote:
>
>> Eduardo M KALINOWSKI wrote:
>>> Barclay, Daniel wrote:
...
>>>> ... 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
>>>> ...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?
>>> ... why make things more complicated and not automatic?
>> ...  I _am_ trying to avoid the
>> complicated and non-automatic solution (trying to check whether the
>> simpler solution is reliable).
...

> 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:
>
> jack@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.

But if you haven't had any disk-failure incidents, do you know whether
your setup will reliably work if either disk fails?  (Did you mean that
you simulated disk failure?)



Daniel
--
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