[Novalug] Problems with debian software raid install.

Joel Fouse joel@fouse.net
Mon Oct 8 14:11:19 EDT 2007


Well, if you're doing softward raid then no, you need to be able to boot
BEFORE the system can even figure out the raid volumes.  If /boot is on
raid, then the hardware better be able to read the raid volumes all by
itself without an OS running.  But it sounds like you're talking
software raid, not hardware raid, in which case /boot can't be a part of
the raid set.  

<Untested Speculation> 
It seems to me you could, however, have /boot as a small partition by
itself on both drives, and just manually copy stuff from one to the
other to keep it in sync.  That way you'd always be booting off of one
but have the other as a fallback in case the first bombed.  You'd want
to install grub in the MBR of both drives as well that way.
</Untested Speculation>

- Joel

p.s. It seems to me that these wizard-based installers that happily set
up LVM for you should be able to throw a warning flag if they notice
you're installing your boot stuff inside a software-based raid set.

On Mon, 2007-10-08 at 13:57 -0400, David A. Cafaro wrote:

> hi Miguel,
> 
> Actually it's important that all the important stuff that's need for  
> boot must be on raid (so that recovery is quick, and a drive failure  
> doesn't lead to a system that can't run).  This server must be geared  
> for uptime, so all systems need to be on raid, including swap.  I've  
> done this on RedHat machines so I know it can be done with Linux,  
> just have to figure out if it's a Debian issue or hardware issue  
> (bios setting or something).
> 
> Thanks though,
> David
> 
> 
> On Oct 8, 2007, at 1:38 PM, Miguel Gonzalez Castaños wrote:
> 
> > Hi,
> >
> >  It's a long time since I don't configure a software RAID, but I  
> > remember that the swap and the / (root) partitions I excluded them  
> > from the RAID. All the important stuff to boot the machine IMHO  
> > should be outside your RAID. If you can, I'd suggest to plug a  
> > third hard drive and create partitions for swap and / (var, usr,  
> > etc, should go also here IMHO).
> >
> >  Miguel
> >
> > David A. Cafaro escribió:
> >> Ok, I need some help.  I'm normally a RedHat/CentOS/Fedora person,  
> >> but for this project I needed to go with Debian.  One requirements  
> >> is that the two 160GB hardrives be setup to provide software  
> >> raid.  No problem the Debian installer seems to handle that no  
> >> problem and I'm able to setup everything how I would like:
> >>
> >> /dev/hda1 108GB raid1 bootable flag
> >> /dev/hda2 20GB raid1
> >> /dev/hda3 20GB raid1
> >> /dev/hda4 2GB raid1
> >>
> >> /dev/hdc1 108GB raid1 bootable flag
> >> /dev/hdc2 20GB raid1
> >> /dev/hdc3 20GB raid1
> >> /dev/hdc4 2GB raid1
> >>
> >> /dev/md0 108GB / raid1
> >> /dev/md1 20GB /home raid1
> >> /dev/md2 20GB /tmp raid1
> >> /dev/md3 2GB swap raid1
> >>
> >> (that's roughly how it's setup)
> >>
> >> All seems to go well debian install goes right through and  
> >> installs all the software, claims grub is installed and reboots.   
> >> At which point I get a no bootable device found.  I think maybe  
> >> grub didn't get install correctly so I try booting into debian  
> >> rescue.  Debian can't mount the raid, doesn't see it, just the raw  
> >> raid partitions.  Just for kicks I boot Fedora 6 rescue, it sees  
> >> the partitions no problem and mounts them all for me to work  
> >> with.  So from Fedora 6 rescue I chroot and reinstall grub,  
> >> reboot, and still no boot devices.  Then I find the following  
> >> article:
> >>
> >> http://valery.bgit.net/blog-en/2006/07/30/debian-installer-sata- 
> >> and-software-raid/
> >>
> >> And figure I'll give that a shot.  I step through the whole  
> >> article (converting SATA to PATA instructions) and no problem,  
> >> reboot and no bootable devices.  At this point I've started trying  
> >> to play with the bios settings to see if that helps, I'm just  
> >> wondering if there is a known issue with Debian Grub and booting  
> >> from software raid devices (which should not be a challenge like  
> >> this).  Any clues?
> >>
> >> And this is Debian Etch v 4.0 r1 i3.
> >>
> >> Thanks,
> >> David
> >>
> >>
> >> David A. Cafaro <dac@cafaro.net>
> >> Cafaro's Ramblings:  www.cafaro.net
> >>
> >>
> >>
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> >>
> >
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> 
> David A. Cafaro <dac@cafaro.net>
> Cafaro's Ramblings:  www.cafaro.net
> 
> 
> 
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