[mythtv-users] Mirroring via LVM or RAID?

Sage sage at gypsycaravan.com
Sat Jul 8 07:45:57 UTC 2006


I'm not entirely sure we're talking about the same thing.  If you
install a new kernel or a new boot image, then no, you don't have to
update grub.  However, if you install a new version of grub, don't you
have to install it again?

Chris's claim is that lilo will install on both disks automatically --
I wasn't aware of this, but I suspect that lilo may be installing onto
the actual boot partition instead of the master boot record.  Grub
defaults to the master boot record, but if I recall correctly, you can
make it install to the first partition instead, at least in Fedora.
Most modern distributions use grub by default, so hopefully grub will
automatically support RAID 1 boot partitions in the future.  But I
know for a fact that it doesn't right now, because I just tried
booting the second disk on my own system yesterday, and no dice.  It's
got to be manually installed.  Maybe this is something that can be
done by the distribution, rather than needing to be built into grub?

On 7/8/06, Debabrata Banerjee <davatar at comcast.net> wrote:
> Grub works just fine it's just poorly documented, you only have to install
> it _once_ regardless of changes. it's superior to lilo in this way.
>
> device (hd0) /dev/hda
> root (hd0,0)
> setup (hd0)
>
> device (hd0) /dev/hdb
> root (hd0,0)
> setup (hd0)
>
> Does this make sense?
>
>
> From: <chris at cpr.homelinux.net>
> > 2. Even if you have your /boot partition on a software RAID 1, the
> > bootloader is only installed on one disk.  Which means that if your
> > first disk dies, even if the other disk is still alive, you can't boot
> > into it.  You can fix this by manually installing grub onto the second
> > disk, but you have to remember to do so every time you update grub
> > (which probably won't be often).
>
> If you use lilo instead of grub then it will install the boot data
> on both drives of a raid mirror so you never have to remember to do
> a second update.  Since both drives are bootable, the loss of hda
> doesn't prevent you from booting the machine (although you will
> need to swap cables if your BIOS doesn't support booting from the
> second interface).
>
>
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