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Re: rootdelay=9 kernal option - why?



On Sat, Jan 7, 2012 at 10:11 AM, Pascal Hambourg <pascal@plouf.fr.eu.org> wrote:
> Hello,
>
> Camaleón a écrit :
>>
>> I wonder how did you finally reached the conclusion for the "rootdelay",
>> I wouldn't either have imagined so after finding any clue over Internet,
>> forums and mailing lists... even after reading the Relase Notes, you still
>> have to connect the points to identify your booting problem with the solution
>> showed there.
>
> OP : "Without it, the root file system is not found and it drops you
> into the initramfs prompt."
>
> Release notes : "The usual symptoms are that the boot will fail because
> the root file system cannot be mounted and you are dropped into a debug
> shell."
>
> Quite similar, isn't it ?

I'm sure I didn't learn of the solution initially through the debian
release notes.

Today if this happens, there are 3 hints shown on the screen and
"rootdelay" is one of several cause/solutions listed.  However the first
time it happened, I needed some googling to find the answer, and
the system was down during the middle of a Debian upgrade until
I did see the solution.

>
>> It is still unclear why you're seeing the error, unless you're at any of
>> the mentioned scenarios (using USB disks, RAID or LILO) the timing
>> problem should not bit you.

Older SCSI disks and controllers (2002 to 2006 vintage) running mirror boot
disks with mdadm seems to trigger the flaw often here.  We're poor,
but we are in the first world.  I can imagine this problem coming up
often in other parts of the world.  The kernel/initramfs folks
should remember not everyone can green their equipment as
frequently as some would like to.


> OP : " We typically have mdadm style software raid on all boot systems,
> using /dev/md0 typically as root file system."
>
> To the OP :
> This is not specific to Squeeze, the issue was already reported in Etch
> and Lenny release notes. And it is not a kernel issue but an initramfs
> issue.

The solution is within kernel params.  Thus I'd think there is some room
for the kernel to be part of the solution, or at least talk to the initramfs
folks to explain the problem.

My hardware is staying the same.  It is the adoption of a newer kernel
that is breaking things.  Release notes do not prevent problems
like this but offer a band-aid.  Again, the release notes description
of the symptoms and solution is not detailed enough to appear
in search results.


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