RE: [Xen-users] dom0's LVM partition in domU

Hello,

I do not if I understand correctly the situation, but I think this is the problem to share the LVM partition. The partition should be used exclusively from Dom0 or DomU, You cannot mount the LVM in Dom0 and hen use if also in DomU (or, you should use it in DomU as read only, but I’m not sure if this is supposed to work). From my „point of knowledge“ LVM cannot handle the concurrent accesses of such multiply mounted partitions. Also if You use a HVM DomU then You cannot either start the DomU if the partition is mounted in Dom0. Maybe it is a little bit different situation in PV domain, but I would never try it to share one LVM block device to multiple mounts unless there is only one write-enabled and all other would be read-only...

With regards, Archie

From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Markus Gerber
Sent: Thursday, December 06, 2007 2:50 PM
To: Emre Erenoglu
Cc: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] dom0's LVM partition in domU

# Kernel + memory size

kernel = '/boot/vmlinuz-2.6.22-14-xen'

ramdisk = '/boot/initrd.img-2.6.22-14-xen'

memory = '512'

# Disk device(s).

root = '/dev/sda1 ro'

disk = [ 'phy:data/dom1-disk,sda1,w', 'phy:data/dom1-swap,sda2,w', 'phy:/dev/mapper/data-share,xvda1,w' ]

The modules are all in /lib/modules. 'depmod -a' and a reboot didn't change anything.

Markus

On 06.12.2007, at 14:40, Emre Erenoglu wrote:

It's getting strange. Normally, the DomU kernel shall detect the xvda that we are exporting. Last point, can you paste your kernel and initramfs lines in DomU config file as well as the disk= line ?

Another: do you have the modules of 2.6.22-14-xen kernel in /lib/modules of the DomU system? have you issued a depmod -a even though these modules shall be in the kernel or initramfs anyway (just to make sure).

Emre

On Dec 6, 2007 2:36 PM, Markus Gerber < markus@xxxxxxxxxxxxx> wrote:

dom1:

uname -a

Linux dom1 2.6.22-14-xen #1 SMP Mon Oct 15 00:35:38 GMT 2007 i686 GNU/Linux

dom0:

uname -a

Linux dom0 2.6.22-14-xen #1 SMP Mon Oct 15 00:35:38 GMT 2007 i686 GNU/Linux

While installing xen, I only used official released XEN packages - no backports etc. I installed dom1 using bootstrap.

Markus

On 06.12.2007, at 14:32, Emre Erenoglu wrote:

Which kernel are you using? can you tell us the output of uname -a ?

If /dev/xvd* does not exist even though you're put disk= line in the DomU config file, it may mean that your kernel is not a PV-enabled one. Usually, what we do is to use DomU kernel of the specific distribution, or worst case, use the dom0 kernel for domU also.

Emre

On Dec 6, 2007 2:29 PM, Markus Gerber <markus@xxxxxxxxxxxxx> wrote:

ls -la /dev/xv*

ls: /dev/xv*: No such file or directory

(in dom1 and dom0)

I'm using para virtualization.

When I uncomment the line in dom1's fstab, I can boot without any error, but I don't get another output calling ls -la /dev/xv*

Markus

On 06.12.2007, at 14:20, Emre Erenoglu wrote:

Can you please give the output of the following command:

ls -la /dev/xv*

Are you using a PV domain or a HVM domain? (full or para virtualization?)

Emre

On Dec 6, 2007 2:17 PM, Markus Gerber < markus@xxxxxxxxxxxxx > wrote:

What I did so far:

- Added the LVM-partition to the dom1's config ('phy:/dev/mapper/data-share,xvda1,w') in dom0

- Added /dev/xvda1 /mnt/share ext3 defaults 0 1 to /etc/fstab in dom1

I still get the very same error while booting.

Are there more steps to do? Mounting /dev/mapper/data-share in dom0 works and i can copy files to it.

Markus

On 06.12.2007, at 13:57, Emre Erenoglu wrote:

As Sadique indicated, try using xvda instead of sda or hda.

Emre

On Dec 6, 2007 1:49 PM, Markus Gerber wrote:

Hello Emre,

These devices do not exist in dom1.

Can I create them manually? Or do I need to install additional packages.

Uups: I've just seen that there is a typo in my first post - dom1 is running Debian Etch and not Ubuntu. Sorry about that!

Thanks and regards,

Markus

On 06.12.2007, at 11:08, Emre Erenoglu wrote:

Markus,

Does it really not exist or just not formatted?

mkfs.ext3 /dev/sda3

and instead of sda, I think you shall consider using xvda (if you're on a PV domU or HVM with PV drivers)

can you see these devices in /dev?

Emre

On Dec 6, 2007 10:51 AM, Markus Gerber <markus@xxxxxxxxxxxxx> wrote:

Hello,

Thank you for your tipp. Unfortunatly, I get an error when booting dom1 saying:

Loading device-mapper support.

Checking file systems...fsck 1.40-WIP (14-Nov-2006)

fsck.ext3: No such file or directory while trying to open /dev/sda3

/dev/sda3:

The superblock could not be read or does not describe a correct ext2

filesystem. If the device is valid and it really contains an ext2

filesystem (and not swap or ufs or something else), then the superblock

is corrupt, and you might try running e2fsck with an alternate superblock:

e2fsck -b 8193 <device>

fsck died with exit status 8

failed (code 8).

* File system check failed.

In my dom1's config file I added the last 'phy' to the disk

disk = [ 'phy:data/dom1-disk,sda1,w', 'phy:data/dom1-swap,sda2,w', 'phy:/dev/mapper/data-share,sda3,w' ]

How does the /etc/fstab in dom1 has to look like? I added:

/dev/sda3 /mnt/share ext3 defaults 0 1

With the line above it does not work. /dev/sda3 does not exist.

Thank you for some more hints.

Regards,

Markus

On 06.12.2007, at 10:13, Emre Erenoglu wrote:

Just a disk= line would suffice. example:

disk = [ 'phy:/dev/volume-group/volume-name,hda1,w' , 'phy:/dev/md1,hda2,w' , 'phy:/dev/volume-group/volume-2,hda3,w' ]

/dev/volume-group/volume-name being one of your LVM volume. (or /dev/mapper/volume_group-volume_name

Br,

Emre

On Dec 6, 2007 9:37 AM, Markus Gerber < markus@xxxxxxxxxxxxx> wrote:

Hello,

In my dom0 (Ubuntu 7.10) I have several LVM partitions (for mp3s,
photos, ...).
Since I do not want to have any services in dom0, I have a domU (also
Ubuntu 7.10) with Samba. So my users connect to that domU. How can I
export and import these LVM partitions from dom0 into domU?

Using nfs could work, but I prefer a solution where my LVM partitions
are 'natively' in domU.

Thank you for some hints and tipps.

Regards,
Markus
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RE: [Xen-users] dom0's LVM partition in domU