Re: [Xen-users] LVM on dom0?

["Lonny Selinger" <lonny@xxxxxxxxxxxxxxxxxxxxxxxx>]

> I've spent the past while researching this but I'm just not finding a
solution. I've been trying to get my xen kernel booting on a pretty much
stock
> CentOS 4.4 installation. I installed Xen from src rpm and installed all the
requisite software and I'm sure it's with the ram disk but I can't figure
out
> how to resolve this.
>
> With a stock kernel here is how my disk is layed out:
>
>
> Filesystem            Size  Used Avail Use% Mounted on
> /dev/mapper/VolGroup00-LogVol00
>                       219G  2.8G  206G   2% /
> /dev/hda1              99M   25M   70M  27% /boot
> none                  252M     0  252M   0% /dev/shm
>
>
> Here is my grub.conf file:
> default=0
> timeout=5
> splashimage=(hd0,0)/grub/splash.xpm.gz
> hiddenmenu
> title XEN (2.6.16.33-zen)
>         root (hd0,0)
>         kernel /xen.gz dom0_mem=131072 noreboot
>         module /vmlinuz-2.6.16.33-xen_3.0.4.1
> root=/dev/mapper/VolGroup00-LogVol00 rhgb quiet
>         module /initrd-2.6.16.33-xen_3.0.4.1b.img
> title CentOS (2.6.9-42.0.8.EL)
>         root (hd0,0)
>         kernel /vmlinuz-2.6.9-42.0.8.EL ro root=/dev/VolGroup00/LogVol00
rhgb
> quiet
>         initrd /initrd-2.6.9-42.0.8.EL.img
> title CentOS-4 i386 (2.6.9-42.EL)
>         root (hd0,0)
>         kernel /vmlinuz-2.6.9-42.EL ro root=/dev/VolGroup00/LogVol00 rhgb
> quiet
>         initrd /initrd-2.6.9-42.EL.img
>
> For my root assignment in the XEN definition I've treid what was originally
suggested and kept it the same as the other kernels
> (root=/dev/VolGroup00/LogVol00) as well as what I had seen in someone elses
config and what my current configuration shows
> (root=/dev/mapper/VolGroup00-LogVol00). I used the initrd created when I did
the initial install of Xen as well I created another one just to make sure
everything would be included but I'm still getting the error that VolGroup00
can not be found.
>
> The error is the same no matter what I set root to which leads me to believe
I'm missing something else in the initrd.
>
> Can anyone please shed some light here? I'm getting ready to manually create
an initrd but it's a bit extreme as I'm sure there is an easy solution to
this. Any help is greatly appreciated!!
>

I was hoping to not make this a huge thread but I figure I better keep it all
in context. I took both initrd images (the centOS 4.4 updated kernel and the
xen package created kernel). The two versions are:

initrd-2.6.16.33-xen_3.0.4.1
initrd-2.6.9-42.0.8.EL

I created two subdirectories off of the main boot directory to un-archive both
ram disk images, one to orig and one to xen, and then ran diff against them:


# diff orig/ xen/
Common subdirectories: orig/bin and xen/bin
Common subdirectories: orig/dev and xen/dev
Common subdirectories: orig/etc and xen/etc
diff orig/init xen/init
21a22,23
> echo "Loading scsi_transport_spi.ko module"
> insmod /lib/scsi_transport_spi.ko
23a26,27
> echo "Loading ide-disk.ko module"
> insmod /lib/ide-disk.ko
Only in xen/: initrd-2.6.16.33-xen_3.0.4.1
Only in orig/: initrd-2.6.9-42.0.8.EL
Common subdirectories: orig/lib and xen/lib
Common subdirectories: orig/loopfs and xen/loopfs
Common subdirectories: orig/proc and xen/proc
Common subdirectories: orig/sbin and xen/sbin
Common subdirectories: orig/sys and xen/sys
Common subdirectories: orig/sysroot and xen/sysroot

Everything looks the same except for the actual init where in the xen ramdisk
ide-disk and scsi_transport_spi are loaded. I did a resursive diff also even
though I know since they are different kernels, some/all of the binaries are
going to be different:

# diff -r orig/ xen/
File orig/dev/console is a character special file while file xen/dev/console
is a character special file
File orig/dev/null is a character special file while file xen/dev/null is a
character special file
File orig/dev/ram is a block special file while file xen/dev/ram is a block
special file
File orig/dev/systty is a character special file while file xen/dev/systty is
a character special file
File orig/dev/tty1 is a character special file while file xen/dev/tty1 is a
character special file
File orig/dev/tty2 is a character special file while file xen/dev/tty2 is a
character special file
File orig/dev/tty3 is a character special file while file xen/dev/tty3 is a
character special file
File orig/dev/tty4 is a character special file while file xen/dev/tty4 is a
character special file
diff -r orig/init xen/init
21a22,23
> echo "Loading scsi_transport_spi.ko module"
> insmod /lib/scsi_transport_spi.ko
23a26,27
> echo "Loading ide-disk.ko module"
> insmod /lib/ide-disk.ko
Only in xen/: initrd-2.6.16.33-xen_3.0.4.1
Only in orig/: initrd-2.6.9-42.0.8.EL
Binary files orig/lib/aic7xxx.ko and xen/lib/aic7xxx.ko differ
Binary files orig/lib/dm-mirror.ko and xen/lib/dm-mirror.ko differ
Binary files orig/lib/dm-mod.ko and xen/lib/dm-mod.ko differ
Binary files orig/lib/dm-snapshot.ko and xen/lib/dm-snapshot.ko differ
Binary files orig/lib/dm-zero.ko and xen/lib/dm-zero.ko differ
Binary files orig/lib/ext3.ko and xen/lib/ext3.ko differ
Only in xen/lib: ide-disk.ko
Binary files orig/lib/jbd.ko and xen/lib/jbd.ko differ
Binary files orig/lib/scsi_mod.ko and xen/lib/scsi_mod.ko differ
Only in xen/lib: scsi_transport_spi.ko
Binary files orig/lib/sd_mod.ko and xen/lib/sd_mod.ko differ

Now technically they SHOULD be different and loading the modules created for
the kernel I'm trying to load so I still don't understand why I can't boot the
xen kernel and have it recognize the volume group. Has no one else run into
this at all?

I'll keep poking but so far less and less is making sense. Both initrd files
were built for their respecive kernels, but only the non xen one finds the vg.
Hopefully some point of enlightenment comes about soon, I'm starting to feel
"new" again ;-)

---
Lonny
-- 
"The glass is neither half empty nor half full ... it is twice as big as it
needs to be"





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