RE: [Xen-users] Root fs on LVM on software RAID1?

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of 
> Mark Turner
> Sent: 23 February 2006 13:25
> To: xen-users@xxxxxxxxxxxxxxxxxxx
> Cc: Mark Turner
> Subject: Re: [Xen-users] Root fs on LVM on software RAID1?
> 
> On 23 Feb 2006, at 11:50, Petersson, Mats wrote:
> > [snip big chunk of mkinitrd problems which I'm not trying to help 
> > resolve - I can just barely make it work when I do it myself... ;-)]
> 
> :)
> 
> > For Xen, you should not use initrd command in grub to load initrd - 
> > you want to use module to load the initrd too. So the line would be 
> > "module /initrd.img-xen-2.6.12.6-xen"
> >
> > This will avoid the Error 19 problem - it obviously won't fix any 
> > problems with creating your initrd... ;-)
> 
> Thanks for the tip. It did fix the error 19 problem. I'm 
> learning a lot here.
> 
> I'm now using the following:
> 
>       title Xen 3.0 / XenLinux 2.6
>       kernel /xen-3.0.gz dom0_mem=262144 
> root=/dev/mapper/group1-dom0slash ro console=tty0
>       module /vmlinuz-2.6.12-xen root=/dev/mapper/group1-dom0slash
>       module /initrd.img-xen-2.6.12.6-xen  
> root=/dev/mapper/group1-dom0slash
> 
> I also tried with:
> 
>       module /initrd.img-xen-2.6.12.6-xen
> 
> The kernel does load now, but it falls over during boot with 
> an error that flashes past so quickly that I can't read it. 
> I've tried videoing it using my phone but the quality is too 
> low. I *think* it says something about failing to mount, and 
> maybe initrd. Currently working on ways to capture the error 
> message so that I can read it.  
> If all else fails then I'll use a decent video camera tomorrow.

If you give xen a "noreboot" option, it won't try to reboot when it
crashes, which will help figuring out what the error is. 

Of course, even better is to have a serial port connected to another
machine and log the data to a file - saves a lot of typing if you want
to send it to the list ;-)

I think the message you'll see is that the system failed to mount the
rootfs, which usually means either:
* udev (or devfs) isn't working right - thus /dev/mapper/<whatever> is
not available when trying to mount /
* the drivers for the hard-disk-controller and/or file-system(s) is not
in your initrd [or in the kernel itself]. 

I've had both problems on my machine(s), and the fix is really to figure
out what is causing the problem and figuring out which option in your
config file needs to be twiddled to fix it. Unless you've done it
several times before, it usually means a large number of kernel builds,
mkinitrd and reboots. 

--
Mats
> 
> Cheers,
> 
> Mark.
> 
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