Xen users - Feb 2009 - Best way to migrate Xen Disk IMG w/LVM''s to a block-device? (e.g. DRBD)

Hi All,

I was hoping to pick someone''s brain about the best way of moving a Xen
disk image (which has LVM''s inside of it) to a new block-device?  I
have the target DRBD device ready but unsure what''s the best &
safest way to do it.

I was actually tempted to mount the Xen disk image in a dom0, and make
it visible via loop devices and promote that DRBD node for the Xen disk
image to primary and flip overwrite-data-of-peer and make DRBD sync it
but there must be an easier, faster, safer way.

Thanks in advance!

-- 
Daniel Kao
Übermind, Inc.
dkao@ubermind.com
Seattle, WA, U.S.A.
+1.206.412.5765 


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> I was hoping to pick someone''s brain about the best way of moving
a Xen disk
> image (which has LVM''s inside of it) to a new block-device?  I
have the
> target DRBD device ready but unsure what''s the best & safest
way to do it.
I did that once by dd''ing data from all filesystems except for the
root-fs onto the new device from withing DomU, then shutting down the
virtual machine, and copying the root-fs from Dom0. kpartx is your
friend for that ;)

Regards,

Stefan

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You already tried rsync? if applicable

1- Prepare the server physical:

1.1
apt-get install rsync


1.2
# /etc/rsyncd.conf

max connections = 1
syslog facility = local3
read only = yes
list = yes
uid = root
gid = root

[p2v]
       comment = physical to virtual server
       path = /

1.3
rsync --daemon


2- Prepare new DomU (in this case LVM)

File System Root /

lvcreate -L 50G -n vmname.dsk VGxen # as needed

FS swap
lvcreate -L 2G -n vmname.swp VGxen

3- Format e mount
mkfs.ext3 /dev/VGxen/vmname.dsk
mkswap /dev/VGxen/vmname.swp
mkdir /mnt/vmname
mount /dev/VGxen/vmname.dsk /mnt/vmname

4-
rsync -vaH --numeric-ids --stats --progress --exclude "/mnt/*"
--exclude "/proc/*" --exclude "/sys/*" --exclude
"/tmp/*" --exclude
"/var/tmp/*" \
           --exclude "/var/run/*.pid" --exclude
"/var/run/dbus/system_bus_socket" rsync://192.168.1.123/p2v/
/mnt/vmname/


5 - Finally

5.1 in /mnt/vmname/etc/fstab

# /etc/fstab: static file system information.
#
# <file system> <mount point>   <type>  <options>      
<dump>  <pass>
proc            /proc           proc    defaults        0       0
/dev/xvda1       /               ext3    defaults,errors=remount-ro 0       1
/dev/xvda2       none            swap    sw              0       0

5.2 in /mnt/vmname/etc/inittab:

co:2345:respawn:/sbin/getty 38400 xvc0

5.3 in /mnt/vmname/etc/securetty:

xvc0

5.4 to create /etc/xen/auto/vmname:

import commands
krn_vers = commands.getoutput(''uname -r'')

name =''vmname''
builder = ''linux''
disk = [ ''phy:/dev/VGxen/'' + name '' +
".dsk,xvda1,w'', \
         ''phy:/dev/VGxen/'' + name '' +
".swp,xvda2,w'' ]
memory = 512
vif = [ ''bridge=xenbr0'' ]
kernel = ''/boot/vmlinuz-'' + krn_vers
ramdisk = ''/boot/initrd.img-'' + krn_vers
root = ''/dev/xvda1 ro''
on_poweroff = ''destroy''
on_reboot = ''restart''
on_crash = ''restart''
extra = ''xencons=xvc console=xvc0 video=tty''
vfb = [
''type=vnc,vncdisplay=0,vnclisten=0.0.0.0,vncpasswd=passwd'' ]

6 - copy modules from Dom0 to new DomU
cp -a /lib/modules/$(uname -r) /mnt/vmname/lib/modules/

7-
umount /mnt/vmname

8 -
xm create /etc/xen/auto/vmname -c


source: http://wiki.xen-br.org/index.php?title=P2v-howto

Att,
Horacio Ibrahim

On Wed, Feb 4, 2009 at 6:42 AM, Stefan Kögl <koeglstefan@gmail.com> wrote:
> > I was hoping to pick someone''s brain about the best way of
moving a Xen
> disk
> > image (which has LVM''s inside of it) to a new block-device? 
I have the
> > target DRBD device ready but unsure what''s the best &
safest way to do
> it.
> I did that once by dd''ing data from all filesystems except for the
> root-fs onto the new device from withing DomU, then shutting down the
> virtual machine, and copying the root-fs from Dom0. kpartx is your
> friend for that ;)
>
> Regards,
>
> Stefan
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users
>


-- 
ITIL: "An industry accepted way of doing something, that works" (Aidan
Lawes)


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