Re: [gentoo-user] Re: Can't find init due to inconsistent drive order

[Randolph Maaßen]

2013/7/2 Grant Edwards <grant.b.edwards@×××××.com>

> On 2013-07-01, Grant Edwards <grant.b.edwards@×××××.com> wrote:
>
> > I've just recently run into a problem where sometimes when a machine
> > boots, the kernel can't find init.  This appears to be because my grub
> > configuration line says "root=/dev/sda5" and _sometimes_ the drive
> > that contains my root partition is sdb instead of sda. AFAICT, for the
> > past 30 years the linux kernel was 100% consistent in the order that
> > hard drives were labelled -- but recently that has seems to have
> > changed.
>
> I still haven't figured out why my drives suddenly started getting
> discovered in varying orders.  I think that the SATA drives are always
> in the same order with respect to each other, but sometimes the
> external firewire drive gets discovered before the SATA drives and
> sometimes after the SATA drives.
>
> It looks like my options are:
>
>  1) Keep hitting the reset button until it works.
>
>  2) Unplug or power down the firewire drive when booting.
>
>  3) Set up an initrd for the sole purpose of finding the actual root
>     parition via filesystem label.  [I find this idea rather offensive.]
>
>  4) Build the firewire drive as a module instead of building it into
>     the kernel.  That would delay the discovery of the firewire drive
>     until after root has been mounted.
>
>  5) For the drive with the root parition on it switch from a DOS
>     parition table to a GPT partition table and use the
>     root=PARTUUID=<whatever> kernel option.
>
>
You don't need to switch to GPT for that. I have a DOS partitioned disk and
"blkid" prints the LABEL and UUID for each partition.


>  6) Fix the kernel so it can find root by looking at filesystem
>     labels.
>
> Number 6 (fixing the kernel) is The Right Thing To Do(tm), but it's a
> bit out of scope for the momement.  The "early code" in the kernel
> obviously knows how to read partition tables and also knows about the
> relevent file system, so I'm a bit baffled why it can't look at the
> file system label.
>
> Changing the firewire driver to be a module is probably the simplest
> solution, but it's a kludgy work-around for what is, in my opinion, a
> kernel bug: if you are going to require people to specify an absolute
> disk drive index for the root partition, then you'd better index
> drives in a consistent order from one boot to the next.
>
> Switching to a GPT partition table sounds like the cleanest solution,
> but I need to figure out if the grub (legacy) ebuild includes GPT
> support or not.  I know it's supported by grub2, but I don't really
> feel like switching to grub2 ATM.
>
> --
> Grant Edwards               grant.b.edwards        Yow! But was he mature
>                                   at               enough last night at the
>                               gmail.com            lesbian masquerade?
>
>
>


-- 
Mit freundlichen Grüßen / Best regards

Randolph Maaßen