is RAID uncompatible with root=LABEL ?

doublehp · Guru Joined: 11 Apr 2005 Posts: 473 Location: FRANCE

I have set up the same kernel two different ways in grub.conf:
- root=/dev/md5 odmraid
- root=LABEL=Gentoo odmraid

The first one worrks fine. The second one ends up with "can not mount root".

In busybox, i see that /dev/md* are missing, /proc/mdstat looks like empty

eccerr0r · Posted: Wed Jan 13, 2010 7:39 pm Post subject:

The root=LABEL (I think root=UUID) methods only work with an initrd that understands these labels, as far as I know.
The only other issue is that if you don't have all the modules just right, coupled with ordering of module loading in the initrd, it will fail.

I haven't used genkernel yet, are you using that?
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doublehp · Guru Joined: 11 Apr 2005 Posts: 473 Location: FRANCE

I was using initrd (with all required options and features in genkernel to generate initrd & RAID). What should be required for labels ?

I can publish my config ... if you think you can read it ... or maybe tell me which keywords I should filter to avoid pasting 3k lines ?

I usually use genkernel, but it seems uncompatible with sys-kernel/xen-sources so I will have to stop using it.
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eccerr0r · Posted: Wed Jan 13, 2010 9:33 pm Post subject:

When it fails do you see in the log that it actually assembled the RAID or did the initrd cause the assembly to fail?

As far as I know it should be irrelevant whether initrd is used, both methods - if you use the same kernel - should autodetect and assemble the RAID. Just that you can't mount by label without the initrd. As far as I know, the 'mount' in the initrd needs to be able to support labels (not sure if busybox mount does, I suppose it should)...

I don't use initrd/genkernel...using straight /dev/md1 for my root partition now so I'm stepping on unchartered territory...
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doublehp · Guru Joined: 11 Apr 2005 Posts: 473 Location: FRANCE

loads personalities, detects drives ... the "can't moint root". No other failure.

raw kernel without initrd) works with root=/dev/md3 . Still don't work with root=LABEL=Gentoo

in some cases, root=/dev/md5 does not work. I just think that usig LABELs is some times more secure.
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meyerm · Posted: Tue Feb 16, 2010 3:11 pm Post subject:

When you use genkernel --disklabel is your friend.