[CentOS] Hardware freezes on Dell Optiplex 320 whilebooting(https://bugzilla.redhat.com/show_bug.cgi?id=499204)

Fri Jul 30 00:43:57 UTC 2010
Robert Heller <heller at deepsoft.com>

At Thu, 29 Jul 2010 18:22:07 -0400 CentOS mailing list <centos at centos.org> wrote:

> On Jul 29, 2010, at 5:31 PM, "Jason Pyeron" <jpyeron at pdinc.us> wrote:
> > Is there a yum way of installing lilo? Will it work with the devicemapper?
> > (assumption is no)
> As long a LILO can boot the kernel off /boot and /boot is a Linux or
> MDRAID partition all the device-mapper related stuff will be done
> within the initrd.
> As far as mirrored /boot is concerned, if LILO is set to look in that
> partition and it's file system is ext2/3 it can grab the kernel file.
> It's read-only during boot and the mdraid meta-data is kept at the end
> of the partition, so it should look and behave as a normal ext file
> system.

The only 'tricky' bit is making sure that the LILO MBR stuff is
'mirrored' -- you just need to duplicate /etc/lilo.conf, changing disk
to install lilo on (this is what I use -- I mirror /dev/sdaN with /dev/sdbN):

sed s/sda/sdb/g </etc/lilo.conf >/etc/lilo.conf-b
/sbin/lilo -C /etc/lilo.conf
/sbin/lilo -C /etc/lilo.conf-b

Actually, I don't think lilo cares what file system /boot is.  Unlike
grub, it does not even look at the 'file system' information at all. 
The lilo 'installer' (the program that runs on the running Linux
system), just grabs the LBAs (used to convert to CHS) of the physical
data blocks of the files (/boot/vmlinuz... and /boot/initrd...) and
stores these addresses someplace, and stores the LBAs (used to convert
to CHS) of where this infor is stored in the MBR.  Lilo's boot loader
just does low-level BIOS disk reads to read what it needs to read,
using this raw LBAs (used to convert to CHS) info.  Lilo is *simple* and
*primitive* and is not bogged down trying to be clever.

MD's RAID works at the physical disk I/O level, so the all of the disks
in a RAID1 mirror set have the same data at the same physical disk
locations (same LBAs).

> -Ross
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Robert Heller             -- 978-544-6933
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