[gentoo-user] Re: How does grub assemble a RAID1 for / ??

[Kerin Millar]

On 04/04/2010 19:43, Mark Knecht wrote:

[snip]

>> Aside from all of that, notable options that are going to be required to
>> boot in your case are:
>>
>> CONFIG_MD_RAID1
>> CONFIG_SATA_AHCI
>> CONFIG_BLK_DEV_SD
>> CONFIG_BLK_DEV_SR
>> CONFIG_MSDOS_PARTITION (normally implicit but worth mentioning)
>>
>> That, and the option corresponding with whichever filesystem you use. Also,
>> make sure CONFIG_SYSFS_DEPRECATED_V2 is off or else udev will balk. You may
>> use the forward slash key to search for option names in make menuconfig
>> (never edit .config directly). All needed options should be enabled as<*>.
>>
>> Also, if you're not experienced with kernel configuration and need a
>> skeleton .config with which to begin, I would suggest you take a look at
>> http://kernel-seeds.org.
>>
>> Cheers,
>>
>> --Kerin
>
> Sorry. I was on a Windows box and it looks like putty cut it off.
> Booted into Linux and this looks more correct. (2424 lines in vi on
> that machine and 2424 lines in late on this machine so I think it's
> all there...)
>
> I looked at your suggestions above and they are all set to =y.
> CONFIG_SYSFS_DEPRECATED_V2 is 'not set'.
>
> - Mark
>
> #
> # Automatically generated make config: don't edit
> # Linux kernel version: 2.6.33-gentoo
> # Sun Apr  4 09:56:49 2010
> #

[snip long config]

Ah, that looks better. Not that I've pored over every line, but at first 
glance everything seems to be in order. There are no obvious gotchas 
that I can see, so I'm somewhat puzzled.

Here are a few random things that spring to mind though ...

I would suggest switching off CONFIG_IDE. It may contend for control of 
your hardware with the AHCI driver, assuming that emulation/comptability 
mode is enabled in the BIOS.

The device nodes may be unavailable at the time that they are needed, 
for some strange reason. If you mount the root filesystem from a livecd 
(with no bind mounts), try creating static nodes in dev/:

   mknod /dev/md0 b 9 0
   mknod /dev/md1 b 9 1
   mknod /dev/md2 b 9 2
   mknod /dev/md3 b 9 3

Note that the preferred minor of your array can be determined by 
examining any component partition. For instance, "mdadm -E /dev/sdb3".

Avoid manual specification of the RAID parameters. The kernel should be 
perfectly able to assemble the array by examining the superblocks of 
partitions of type "FD".

Does it work if you specify "root=/dev/sdb3" or "root=/dev/sdc3"? With 
raid1, it's possible to mount just the component partition (although it 
will later result in a resync). The point is, it would at least confirm 
as to whether the underlying block devices are available to the kernel 
from the outset.

Cheers,

--Kerin