CentOS - Apr 2007 - Centos5: RAID1 on root/boot? [+lilo mkinitrd issues]

Hi,

I did a command-line upgrade of a RHL73 server to Centos 5.  It was a 
bit rocky road, but in the end it was successful.

There's one thing that bugged me.  I'm using software RAID1 consisting 
of /dev/hd{a,c}.  No LVM or anything fancy, a number of /dev/mdX 
partitions, including the root (+/boot).

I'd have preferred to continue using lilo as it works more easily with 
RAID1 root/boot setups.  The deployment guide for Centos5 claims to 
support RAID1 boot partitions (RHEL4 didn't, and provided a pointer a 
site in UK which no longer works for more info), it's not clear how 
exactly a redundant boot block configuraton is achieved with that -- 
so that if you remove the primary drive, it'll still boot.

Anyone have pointers for this?

[I've gone through a number of sites with various hacks how to install 
grub on both disks, but I'm not quite sure which ones are valid, and 
whether those are needed anymore]


.. read on if you're interested about the lilo/mkinitrd problem ..

However, lilo doesn't really work, the root cause as far as I've been 
able to go is that '/dev/root' isn't recognized and as such not 
mounted.  With grub this works.

The init script in the initrd includes the following (automatically 
generated): 
===8<=echo Creating root device.
mkrootdev -t ext3 -o defaults,ro /dev/md0
echo Mounting root filesystem.
mount /sysroot
===8<=
And looking at the vast amount of RH bugs about this, it seems this 
root autodetection has caused significant grief, e.g., 
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=197701. 
However, no bugs on this (or similar) have been filed under RHEL5.

Any thoughts?  Anyone run with similar setups?

*)
=======8<===md: autorun DONE
..
Creating root device
Mounting root filesystem
mount: could not find filesystem '/dev/root'
Setting up other filesystems
Setting up new root fs
setuproot: moving /dev failed: no such file or directory
no fstab.sys, mounting internal defaults
setuproot: error mounting /proc: no such file or dir
setuproot: error mounting /sys: no such file or dir
...
and finally, a kernel panic.
=======8<=====
-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings

On Sun, 2007-04-22 at 21:40 +0300, Pekka Savola wrote:
> Hi,
> 
> I did a command-line upgrade of a RHL73 server to Centos 5.  It was a 
> bit rocky road, but in the end it was successful.
> 
> There's one thing that bugged me.  I'm using software RAID1
consisting
> of /dev/hd{a,c}.  No LVM or anything fancy, a number of /dev/mdX 
> partitions, including the root (+/boot).
> 
> I'd have preferred to continue using lilo as it works more easily with 
> RAID1 root/boot setups.  The deployment guide for Centos5 claims to 
> support RAID1 boot partitions (RHEL4 didn't, and provided a pointer a 
> site in UK which no longer works for more info), it's not clear how 
> exactly a redundant boot block configuraton is achieved with that -- 
> so that if you remove the primary drive, it'll still boot.
> 
> Anyone have pointers for this?
> 
> [I've gone through a number of sites with various hacks how to install 
> grub on both disks, but I'm not quite sure which ones are valid, and 
> whether those are needed anymore]
This has been touched on several times in the CentOS mailings. Did you
also search CentOS? If not, ISTR that there are answers there. For grub,
of course.
<snip>

HTH
--
Bill