[clug] dist-upgrade to Debian Lenny - flagged boot problem

Daniel Pittman daniel at rimspace.net
Tue Aug 11 19:11:43 MDT 2009

Felix Karpfen <felix.karpfen at gmail.com> writes:
> Daniel Pittman wrote:
>> Felix Karpfen <felix.karpfen at gmail.com> writes:
>>> The Debian Lenny Release Notes include the following entry:
>>>  4.8. System boot hangs on Waiting for root file system
>>>  Procedure to recover from /dev/hda that became /dev/sda
>> [...]
>>> Given that only "some users" encounter this problem, what do I have to do to
>>> not fall into this "some user" subdivision?
>> Mount by label or UUID,
> This says in 5 words what the release notes describe in some detail (and I
> considered to be a PITA).

I /think/ you mean the solution, and not the five word version of the release
notes, here. :)

Anyway, moving to some physically independent solution to mounting is a good
idea; recent kernels are moving more and more to asynchronous probing, which
means that if you have multiple physical HBAs[1] you will *NOT* have a
predictable device detection order over boot.

> While I have now located the needed details for UUID mapping, the release
> notes - which assume that I use GRUB to boot - do not give me any guidance
> on what needs changing in /etc/lilo.conf.

Well, assuming you use the stock initrd, "root=UUID=whatever" in the kernel
command line is all you need.

> Specifically how do I identify the location of the MBR under the new
> system. Currently, the relevant entry in /etc/lilo.conf reads:
> "boot=/dev/hdb"; "hdb" does not have a UUID.

lilo doesn't support anything but physical devices at that level, as far as I
can tell, nor does it support the EDD information that exports the physical
device to BIOS device number mapping to Linux.

Your best bet is probably to identify what the BIOS considers the physical
boot device, then use the links in /dev/disk/by-id/ata-* to identify the same
physical device reliably by serial number or whatever.

Then you can use the devicemap stuff to map those portably symlinks to the
BIOS device numbers.

>> or use MD or LVM, at which point your filesystem is found independent of
>> the underlying physical hardware.
> New territory for me - which I would prefer to "not enter".
> Thank you for the prompt response.

I hope it helped.  I had assumed you would ask further questions if the five
words were not enough ... and I did expect they were not.  It is just the case
that with so many different answers something comprehensive would fill out the
release notes. ;)


[1]  ...and most of us do, these days, at least in laptops.  Desktops, maybe
     not quite so much.  Typically in the form of an Intel chipset with two
     controllers built in.

✣ Daniel Pittman            ✉ daniel at rimspace.net            ☎ +61 401 155 707
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