From: Shachar Shemesh (linux-il_at_nonexisting.hamakor.org.il)
Date: Sat 01 May 2004 - 18:16:14 IDT
Ok, here is my take on the matter:
First of all, if unattended kernel replacements or RAID root FS are not
important to you, GRUB gobbles up LILO any day of the week. It is faster
to load, more resiliant to configuration errors, and more secure when
you try to lock down the config using boot password. However, it does
have two missing features:
1. LILO -R
on Lilo, this changes the default for the next reboot only. This allows
you, when remotely replacing a kernel, to give the new kernel a try
before commiting to booting from it always. Upon replacing the kernel, I
do the following:
lilo -D failsafe
lilo -R newkernel
reboot
If everything is ok (uname -r shows I'm with the new kernel), I go back
to root, and do
lilo
no configuration file changes.
It is possible to set a similar setup with grub. It basically exploits
the fact that grub's "default saved", and particularily "savedefault",
do not distinguish between the main menu and submenus. What you do is this:
Set up grub as usual. Get menu.lst to have a first entry pointing to a
submenu. Have the second entry pointing to another submenu. The first
entry will be the kernel you want to check out, and the second will be
the regular menu.
In the runonce menu, you set a dummy first option, and you set the
second option to be the tryout menu. You give it a "savedefault" option.
Because this is the second entry of the menu, and because GRUB doesn't
tell the second level from the first, the main menu will boot from the
second option in the main menu the next time around.
Source: http://savannah.gnu.org/bugs/?func=detailitem&item_id=557
Disadvantages:
1. Need fairly comples config file changes each time you want to perform
this trick.
2. Need to get the "savedefault" to point to the first entry to begin with.
3. You lose the capacity to use "update-grub" to update the config
files. It can update one of them, but you will have to copy the config
to the other one each time.
In short, this is error prone, and no replacement to lilo's -R option.
2. Setting "boot=/dev/md0" and "root=/dev/md0"
It's not perfect in lilo either. You will, essentially, need to install
a master boot record on all disks participating in the array. However,
once you've done that (once), the above will correctly install lilo, and
will allow you to boot from either disks.
In grub, things are more difficult, though not impossible.
Manually install GRUB on both disks, and use the "fallback" option to
jump from one to the other if there was a disk failure.
If you don't need the "fallback" solution for anything else (and let's
face it - lilo doesn't have this feature at all, so if that is the sole
criteria for lilo vs. grub, it's nothing crucial), it should be a fairly
acceptable solution.
I hope this helps,
Shachar
-- Shachar Shemesh Lingnu Open Source Consulting http://www.lingnu.com/ ================================================================= To unsubscribe, send mail to linux-il-request_at_linux.org.il with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail linux-il-request_at_linux.org.il
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