lilo vs grub

Alexandre Oliva aoliva at redhat.com
Mon Oct 20 16:50:08 UTC 2003


On Oct 20, 2003, Chris Ricker <kaboom at gatech.edu> wrote:

> grub only gets installed to one of the two disks in the mirror. If that one
> fails, you can't boot.

> This is because grub can't be installed to /dev/md?. LILO, in contrast, can.

> You can work around it by manually installing GRUB to both components in the 
> mirror, but that's lame....

I find it better to be sure it works that being fooled into believing
it would work and then, just when you most need it, finding out it
doesn't, like it happened to me.

See, /boot on raid1, and I thought this would save my life when I disk
died.  Today I know better.

The problem is that, when a disk dies, the BIOS may renumber the
disks.  A mere change in the order of disks to boot from may renumber
the disks, rendering all the settings stored in the disks useless.

Also, if the actual /boot partitions happen to not be at the very same
disk locations, or the disks don't have equivalent geometry, you
lose.  And don't even get me started on installing the boot loader in
the first sector of the partition, instead of in the MBR.

Unless lilo support for raid1 has improved a *lot* since I last used
it, and I don't really see how to overcome most of the issues above,
saying it supports raid1 is a fallacy.  It may get you that warm fuzzy
feeling that it's actually going to save you, but unless you actually
test the failure scenario and make sure it works, I'd feel much better
knowing I'd better have a rescue disk handy.

FWIW, this is not meant as a rant against lilo; raid1 in grub can be
no better, for the same reasons.  The only difference is that it won't
give you that warm fuzzy feeling that you're safe when you actually
aren't.  You may get yourself into this trap if you think you know
what you're doing but not really :-), but then that's not grub's
problem.

-- 
Alexandre Oliva   Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/
Red Hat GCC Developer                 aoliva@{redhat.com, gcc.gnu.org}
CS PhD student at IC-Unicamp        oliva@{lsd.ic.unicamp.br, gnu.org}
Free Software Evangelist                Professional serial bug killer





More information about the fedora-test-list mailing list