Re: metadata and / and grub-static

[Mark Knecht <markknecht@gmail.com>]

On Sun, Apr 4, 2010 at 12:34 PM, Mark Knecht <markknecht@gmail.com> wrote:
> Hi,
>   I'm trying to do my first RAID install that puts / on RAID1 but I'm
> having some trouble. Distro is Gentoo. I'm fairly certain the problem
> is in my kernel because grub finds my RAID enabled kernel and starts
> booting, but when it gets to the point where it is going to enable md0
> and mount / (or I think that's where it is) then it fails with a very
> standard message:
>
> VFS - Unable to mount root fs on unknown-block(9,0)
>
>   I know the machine works because I already have a non-RAID install
> on sda. The new RAID install is on sdb & sdc and I'm booting to it
> from sda. However so far I cannot get past the point where it figures
> out what to do with /dev/md0 and moves on.
>
>   I just wanted to check that the messages below, which occurred when
> I first built the RAID, aren't a real killer. I am not storing /boot
> on this device but I do want to store /. Is there any problem with
> recent versions of grub doing this? I chose metadata=1.0 as mdadm
> seemed happier with that choice, but I've been unable to mount this
> RAID either.
>
>   Again, if this is a kernel issue then I'll work it out. I've built
> RAID0 and RAID1 support into the kernel, as well as other things, but
> maybe I've missed something else. I just wanted to be doubly sure that
> it's not a problem with grub as a boot loader.
>
> Thanks,
> Mark
>
> keeper ~ # mdadm --create /dev/md0 --level=1 --raid-devices=2
> /dev/sdb3 /dev/sdc3
> mdadm: Note: this array has metadata at the start and
>    may not be suitable as a boot device.  If you plan to
>    store '/' or '/boot' on this device please ensure that
>    your boot-loader understands md/v1.x metadata, or use
>    --metadata=1.0
> mdadm: Note: this array has metadata at the start and
>    may not be suitable as a boot device.  If you plan to
>    store '/' or '/boot' on this device please ensure that
>    your boot-loader understands md/v1.x metadata, or use
>    --metadata=1.0
> Continue creating array? n
> mdadm: create aborted.
> keeper ~ #  mdadm --create /dev/md0 --level=1 --raid-devices=2
> --metadata=1.0 /dev/sdb3 /dev/sdc3
> mdadm: array /dev/md0 started.
> keeper ~ # cat /proc/mdstat
> Personalities : [raid1]
> md0 : active raid1 sdc3[1] sdb3[0]
>      31463228 blocks super 1.0 [2/2] [UU]
>      [>....................]  resync =  3.9% (1241664/31463228)
> finish=5.2min speed=95512K/sec
>
> unused devices: <none>
> keeper ~ #
>

Answering self - putting / on RAID1 only seems to work using
--metadata=0.90. Tried it with higher versions and had no luck.

Anyway, the system is running well now.

Cheers,
Mark
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