[olug] of Grub and Lilo

[Christopher Cashell]

At Thu, 12 Dec 02, Unidentified Flying Banana Jeff Hinrichs, said:
> Can anyone tell me why one would use Grub instead of Lilo?  From what
> I can see, lilo is better documented and better understood.  Outside
> of Grubs graphical bootup, is it better than lilo at anything else?

There's actually a number of reasons.

First of all, LILO works, for the most part, and for most people.  It's
fairly basic, but it does what it needs to do.  However, it's also
somewhat limited, and there are many things that it can't do (and some
it couldn't do at some point, but have been semi-hacked in).

GRUB provides a true Pre-OS environment, something like a mini-OS,
prior to booting a true OS.  This gives it amazing flexibility and
allows it to do many things that LILO could never dream of.

A few examples of where GRUB is ahead of LILO:

  o GRUB was the first boot-loader to support booting beyond the 1024th
    cylinder of a hard drive.  You can put your boot partition at the
    very end of the drive if you want, and still boot from it.
  o GRUB was the first boot-loader to properly detect systems with
    greater than 64MB of RAM
  o GRUB was the first boot-loader to support the Multiboot standard
    (used by GNU HURD, and others, likely to be used by more systems in
    the future).
  o GRUB has long had a menu based interface available.
  o GRUB is capable of booting BSD kernels directly.
  o GRUB understands file systems itself.
  o GRUB allows you to specify kernel arguments dynamically.
  o GRUB allows you to update it's configuration file without rerunning
    it.
  o GRUB allows you to install new kernels, and use them, without
    rerunning it.
  o GRUB is file system-aware.  It can read file systems directly, without
    the aid of an OS kernel, or a separate utility.
  o GRUB includes an interactive shell, allowing you to do things like
    browse (supported) file systems prior to booting (and you can even find
    specific kernels that way, and boot from them).
  o Due to GRUB's design, it is being developed at a faster rate, with
    new features being included that LILO can't support.
  o GRUB is gaining popularity, with many distributions moving to it
    in favor of LILO, due to it's greater flexibility and features. (I
    believe Red Hat now uses it as the default boot loader, and Debian is
    planning to soon, also.)
  o GRUB's config file is reread with each bootup, so you don't have to
    continually overwrite the MBR every time you change it.  In the
    event of a misconfiguration with another boot loader, you could leave
    the MBR in an unbootable state.  With GRUB, a misconfiguration will
    just drop you to a command line where you can proceed as you choose.
  o GRUB can support diskless systems, and can even download OS images
    from a network.
  o GRUB is very usable in emergency boot situations, as it provides so
    much functionality prior to boot.
  o GRUB provides tab expansion for commands and file system browsing.

GRUB does have a few disadvantages.  Here's the major ones that I'm
aware of:

  o GRUB is big.  LILO is a very small utility that relies on the Linux
    kernel to do most of it's work.  GRUB contains a full command shell
    available for interactive use, and also natively understands each
    file system it supports.
  o GRUB is file system-dependent.  GRUB can only work with file systems
    that it supports.  In rare occasions, this can limit it.  One key
    example was with Linux and XFS.  For a few months after XFS was
    initially released, GRUB didn't support it, and wasn't able to load
    kernels on XFS file systems.  With LILO, it just points to the sector the
    kernel is at on the disk, and simply starts it via that, allowing
    the kernel to handle all FS processing.
  o GRUB is still new, compared to the venerable LILO, and thus lacking
    in documentation.  LILO is almost 10 years old, and has numerous
    how-to's, tutorials, etc, for it.  GRUB has a lot less, though the
    documentation is improving.  There's quite a bit in info format
    available from GNU.

That's about all I can think of at the moment.  All in all, I've become
a fan of GRUB, and I've been slowly converting all of my machines to use
it.  So far, it's gone without a hitch.

> -jeff

--
| Christopher
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| A: No.                                         |
| Q: Should I include quotations after my reply? |
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