[linux-lvm] Changing device numbers.
Andreas Dilger
adilger at turbolinux.com
Tue Mar 13 21:41:39 UTC 2001
Bas writes:
> From: Andreas Dilger <adilger at turbolinux.com>
> > 1) The most important problem is that it is IMPOSSIBLE for LILO to boot
> > from a striped LV (or MD RAID 0 for that matter). No matter what you
> > do, this will not be fixed, because the BIOS cannot handle a kernel
> > image on multiple disks.
>
> To avoid miscommunication: the LV is striped across 2 disks. I'm not using
> RAID or anything like that. To be more specific: I used lvcreate -i2 -I 4 -L
> (size) -n (name) (vgname). The kernel image is on /boot, which is (the
> only) "normal" partition.
Yes, even "-i2" is striping across multiple disks, just like RAID 0. However,
if you have /boot on a normal (DOS) partition, then you are OK.
> > "Niceness" has nothing to do with it. LILO is complaining about not
> > recognizing device "58:15" (or whatever), but it would also complain about
> > device "58:0" until you apply the LILO patch. After that, it will work no
> > matter what you do, as long as LILO is happy with where the kernel is
> > physically located on disk.
>
> Why does it work when I manually type "root=/dev/rootvg/root" ?
Maybe because vgscan is changing the device numbers for /dev/rootvg/root?
It may also be that the initrd has different device numbers for the LVM
devices than the root partition does? If you put a line "root=/dev/vgX/lvY"
in the lilo.conf, it will store the major/minor into the boot parameters.
You probably should use "append=root=/dev/vgX/lvY" to get it correct.
> > Here is the LILO patch again. The LVM patch is in beta6. If you use it
> > with anything older than beta3, it will crash your system.
>
> Just for my understanding: if I use this patch, I will not have to use an
> initrd anymore ?
No, you still need initrd, but you no longer need to keep /boot in a DOS
partition. You DO need to have a boot LV that is not striped (MD RAID 1
mirroring should be OK).
Cheers, Andreas
--
Andreas Dilger \ "If a man ate a pound of pasta and a pound of antipasto,
\ would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/ -- Dogbert
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