Re: Re (2): lilo removal in squeeze (or, "please test grub2")
On Sat, 29 May 2010 10:51:10 -0400 (EDT), Marc Haber wrote:
> On Tue, 25 May 2010 11:42:34 -0400 (EDT), Stephen Powell wrote:
>>
>> You're missing the point. The main selling point to management
>> is that Linux is free. If they have to buy new backup software
>> in order to accommodate Linux' backup requirements, that will
>> kill it on the spot. Whatever boot loader I use must not
>> require new backup software or impose special backup requirements.
>
> From what I guess, your backup scheme is highly hardware dependent
> since lilo uses block lists in the MBR to find its later stages on
> disk.
Strictly speaking, the MBR points to the partition boot sector,
the partition boot sector points to the second stage loader,
the second stage loader points to the map file (/boot/map) and
the map file points to the kernel image blocks and the initial RAM
file system image blocks. But yes, this is location-dependent
information.
> So your restored system will only boot if you restore to a disk
> with the exactly same geometry.
Not if the restore software understands the format of the boot loader
files and knows how to patch them. Fortunately it does. But only
for lilo. And only under certain conditions.
> I would change the restore process to manually reinstall the boot
> loader after the backup software finished with its restore job anyway,
> or you might be surprised with an unbootable restored system if you
> had to restore to different hardware.
That is not an option. When the restore completes it automatically
reboots the machine. Besides, the restore software runs under DOS,
not under Linux. The boot loader installation program won't run under
DOS. If patching the boot loader files was not
successful, the machine won't boot. Manual intervention is necessary
(i.e. boot from a rescue CD, chroot into the root file system, mount
the /boot partition, and re-run the boot loader installation program).
The only way around this problem (other than using smarter software)
is to create an image (sector by sector) backup and do an image restore.
That works with any boot loader. But that has two major drawbacks.
(1) The technician has to remember to do it that way, and (2) it
prevents restoring individual files. You either restore the whole
server or nothing.
As I've stated in other posts, we are aware of the deficiencies of
our backup software and are looking at alternatives. But right now,
this is what we're stuck with. Thanks for the suggestions, though.
--
.''`. Stephen Powell
: :' :
`. `'`
`-
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