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Re: grub-setup: error: no mapping exists for ... in GRUB2 v1.97.1 on fak


From: Lapohos Tibor
Subject: Re: grub-setup: error: no mapping exists for ... in GRUB2 v1.97.1 on fake (IMSM) RAID
Date: Tue, 5 Jan 2010 08:18:54 -0800 (PST)

Thanks for the help. I consider this case closed till GRUB reaches that certain development state.
 
I tried a totally different approach, I guess one would call it "GRUB on pure software RAID", and I bumped into a new problem. I'll describe it under a new thread.
 
Thanks again,
Tibor


--- On Mon, 1/4/10, Felix Zielcke <address@hidden> wrote:

From: Felix Zielcke <address@hidden>
Subject: Re: grub-setup: error: no mapping exists for ... in GRUB2 v1.97.1 on fake (IMSM) RAID
To: "The development of GNU GRUB" <address@hidden>
Date: Monday, January 4, 2010, 4:23 AM

Please use proper quoting. It doestn't make it easier to read if your
answer is directly below my sentences without any special quoting.

Am Sonntag, den 03.01.2010, 20:29 -0800 schrieb Lapohos Tibor:
>
> Thanks for your help. Please see my further questions below.


> Based on your input, I cannot make this work, right?
>

No.
Probable we could implement support for the newly added metadata
formats, but that's IMO very very low priority.
The normal ones are more important, especially now that 1.1 became the
default instead of 0.90.

> I made a Baazar branch for metadata 1.x support, but it's still
> broken.
> At least RAID != 1.

> So it works for RAID 1, and it is "broken" for the other RAID levels?

It seems so. I haven't found out why exactly yet.

> But I tested RAID 1 only with grub-probe, not actual booting from it.
> And it's a bit complicated to get grub-probe working, because the
> devicename must macht the name stored in the superblock.

> Would I need to be able to achieve all this as I am assembling the
> RAID devices?
>

You can also just rename the device files afterwards, but before you run
grub-install or update-grub/grub-mkconfig.

> If you want to try it nevertheless:
>
> bzr co http://bzr.savannah.gnu.org/r/grub/people/fzielcke/raid
>
>
> Thanks, I'll give it a shot once I get a better grasp of what I'm
> doing.
>
>
> device.map isn't used at all for mdraid devices.
>
> But my device is not "mdraid" type device, is it? The kernel does not
> detect it as it loads and starts running. The "mdraid" devices would
> be formed of "fd" type partitions, would they not?
>

No. mdraid devices can have any partition type you want. As with any
Linux filesystem etc. pp.
fd has only the special meaning that Linux autoassembles them. But the
prefered method is to let mdadm inside the initrd/initramfs handle it.
And then it doestn't matter at all what partition type you use.

/dev/mdXXX and /dev/md/XXX are all mdraid devices. As long as mdadm -Q
--detail works on it. Doestn't matter what mdraid metadata you use.

>
> (hdX,Y) devices are normal disk devices though and not the RAID ones.
> They're (mdX) and (mdX,Y) so it only works with RAID 1, but only by
> using one disk of them.

> OK, I understand this. But then I must ask, how come the grub shell
> (got into by booting from a usb key) lists (hdX,Y) devices for all
> these "imsm" contained devices and partitions?

Ok I should have written (hdx,y) devices are normal BIOS devices.

> Thanks again for your help,
> Tibor
--
Felix Zielcke
Proud Debian Maintainer and GNU GRUB developer



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