Re: [gentoo-user] boot failure using root=LABEL=RAID1root but not LABEL=RAID6root

["J. Roeleveld" <joost@antarean.org>]

Mark Knecht <markknecht@gmail.com> wrote:

>Hi,
>   I don't think this is likely to be a Gentoo issue but I figured I'd
>ask here first before going elsewhere. (LKML, linux-raid, elsewhere)
>Additionally it's not a critical problem at all but rather something
>I'd like to try and understand and then report if appropriate.
>
>   On my main i7-980x machine I've been wanting to move root away from
>an old 3-disk 50GB RAID1 that I built first built the machine with to
>a newer 150GB RAID6. Toward this end the machine has two complete
>Gentoo builds on it:
>
>c2stable ~ # cat /proc/mdstat
><SNIP>
>
>md3 : active raid6 sdc3[1] sdd3[2] sdb3[0] sde3[3] sdf3[5]
>157305168 blocks super 1.2 level 6, 16k chunk, algorithm 2 [5/5]
>[UUUUU]
>
>md126 : active raid1 sdd5[2] sdc5[1] sdb5[0]
>      52436032 blocks [3/3] [UUU]
>
>unused devices: <none>
>c2stable ~ #
>
>md126 is the older RAID1, md3 is the newer RAID6. The are both built
>on parts of the 5 hard drives in the box.
>
>The two builds are intended to be identical. Same packages installed,
>same kernel with the only exception being the RAID6 uses an initramfs
>built into it. A diff of the two kernel configs shows only that
>difference:
>
>c2stable ~ # diff /usr/src/linux/.config
>/mnt/newRAID6/usr/src/linux/.config
>137c137,139
>< CONFIG_INITRAMFS_SOURCE=""
>---
>> CONFIG_INITRAMFS_SOURCE="/usr/src/initramfs.config"
>> CONFIG_INITRAMFS_ROOT_UID=0
>> CONFIG_INITRAMFS_ROOT_GID=0
>142a145,146
>> CONFIG_INITRAMFS_COMPRESSION_NONE=y
>> # CONFIG_INITRAMFS_COMPRESSION_GZIP is not set
>c2stable ~ #
>
>   In my grub.conf file I have three methods of booting the machine.
>There are two methods of booting the RAID1 config, using the device
>name and using the label. For the RAID6 I have only the label method:
>
>(NOTE: Snipped out backup kernels just to clarify)
>
>c2stable ~ # cat /boot/grub/grub.conf
>default 0
>timeout 15
>splashimage=(hd0,0)/boot/grub/splash.xpm.gz
>
>title RAID1 3.6.11-gentoo
>root (hd0,0)
>kernel (hd0,0)/boot/bzImage-3.6.11-gentoo root=/dev/md126
>
>title RAID1 3.6.11-gentoo using LABEL
>root (hd0,0)
>kernel (hd0,0)/boot/bzImage-3.6.11-gentoo root=LABEL=RAID1root
>
>title RAID6 3.6.11-gentoo using LABEL
>root (hd0,0)
>kernel (hd0,0)/boot/bzImage-RAID6-3.6.11-gentoo root=LABEL=RAID6root
>
>c2stable ~ #
>
>c2stable ~ # e2label /dev/md126
>RAID1root
>c2stable ~ # e2label /dev/md3
>RAID6root
>c2stable ~ #
>
>
>The results are:
>
>1) RAID1 using md126 boots fine
>2) RAID1 using label of RAID1root fails
>3) RAID6 using label of RAID6root boots fine
>
>   The failure is a kernel crash before the machine gets very far so
>the only capture I might be able to try is with a camera and then post
>that on line, but the screen is 80x25 and it's just a kernel crash so
>there's very little data on the screen when the machine dies.
>
>   I've been Googling around for a couple of days but haven't found
>anything very interesting. I figured I'd ask here first just to see
>what ideas come up.
>
>Thanks,
>Mark

Mark.

I seem to remember that to be able to use LABEL for the root= line requires an init* as you need userspace utilities to read the labels.

You could try the UUIDs instead. But I am not sure if that might work.

HTH

Joost

PS. All the best for 2013!
-- 
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