:state: closed

#4 : Migrating Tups to Mops
===========================

The following is my condensed version of the article `Physical to
container <http://wiki.openvz.org/Physical_to_container>`_ from OpenVZ
Wiki.

See also my blog entries: 
:blogref:`20110520`
:blogref:`20110521`

Context
-------

`tups` is an old machine that has been serving a few websites
for over five years. It has 40 GB of hard disk space, 256 KB of RAM.
The OS is currently a Debian Lenny. 

Now I bought a new machine (500 GB hard disk space and 1 GB of RAM), 
installed Proxmox on it and want to migrate `tups` to a 
container on this machine.

Note: the terms "Virtual Machine" and "Container" are equivalent.

In our LAN, `tups` is running on `192.168.1.101`, 
the new Proxmox server on `192.168.1.160`.

The ProxMox web interface is accessible at `https://192.168.1.160`.
Using :menuselection:`VM Manager --> Virtual Machines --> List --> Create`
I created a "dummy" container with ID 101.

Manually creating a VM using a dummy
------------------------------------

We have a dummy VM with ID 101 and want to create a 
second VM with ID 103 
that will contain `mops`, the successor for `tups`.

::

  cd /var/lib/vz
  mkdir root/103 private/103
  
  cd /etc/vz/conf
  cp 101.conf 103.conf
  nano 103.conf

The web interface would now show the new container,
but of course we cannot yet start it since it is empty.

Copying the data
----------------

We are going to execute the following twice: 
a first time when tups is still running,
and a second time "for real" (when tups is stopped).

I log into the Proxmox server using ``ssh root@192.168.1.160``.

I start a first `rsync` which takes about 5 hours at the first run 
(and much less at subsequent runs)::

  # cd /var/lib/vz/private/103
  # rsync -arvpz --numeric-ids --exclude=/dev --exclude=/proc --exclude=/tmp -e ssh root@192.168.1.101:/ ./
  ...
  sent 7440467 bytes  received 27367553246 bytes  1456310.35 bytes/sec
  total size is 32426725913  speedup is 1.18
  rsync error: some files could not be transferred (code 23) at main.c(1524) [generator=3.0.3]
  
The errors are normal since I didn't stop the services for that first run.

If I'd now try to start `mops` at the web interface, I'd get quite somme error 
messages at the init log. The raw copy of `tups` is not able to live in a VM 
environment, it needs a few manual adjustments.
The following instructions are copied and adapted from the 
Proxmox documentation.

- A container does not have real ttys, so you have to disable getty 
  in /etc/inittab (i.e. /var/lib/vz/private/103/etc/inittab)::

    cd /var/lib/vz/private/103
    sed -i -e 's/^[0-9].*getty.*tty/#&/g' etc/inittab
    
- The `/etc/mtab` of `mops` must be replaced by a sympolic link to `/proc/mounts`::
    
    ln -sf /proc/mounts etc/mtab
    
- Since you do not have any real disk partitions in a container, 
  /etc/fstab (or most part of it) is no longer needed. 
  Empty it (excluding the lines for /dev/pts, /proc, /sys and such)::

    mv etc/fstab etc/fstab.old
    egrep '/dev/pts|/dev/shm|/proc|/sys' etc/fstab.old > etc/fstab
    
- Remove udev's persistent net rules::

    rm etc/udev/rules.d/70-persistent-net.rules    
    rm etc/udev/rules.d/75-persistent-net-generator.rules
    
- Copy complete `/dev` directory from the previously 
  created dummy host::

    mv dev dev.old
    cp -R ../101/dev .
    

Now it's time to start the container, either using ``vzctl start 103`` 
at the command line, or clicking the start button in the web interface.
Apache runs.


The definitive copy
-------------------

Stop most services (but not `ssh`) on `tups`::

    # /etc/init.d/exim4 stop
    # /etc/init.d/mailman stop
    # /etc/init.d/apache2 stop
    
    # /etc/init.d/postfix stop
    # /etc/init.d/postgresql stop
    # /etc/init.d/mysql stop
    # /etc/init.d/samba stop

The second `rsync` on `proxmox` takes much less time. 
It undoes of course all my adjustments::

  rsync -arvpz --numeric-ids --exclude=/dev/ --exclude=/proc --exclude=/tmp -e ssh root@192.168.1.101:/ /var/lib/vz/private/104/

Redo all adjustments, then start `mops` in the Web interface.
check the init log.
Try to log in to `mops` using ssh:::

  ssh root@192.168.1.103
  
Disable services that are no longer needed on a VM:
for SERVICE in `checkfs.sh checkroot.sh console-screen.sh hwclock.sh hwclockfirst.sh lm-sensorsudev udev-mtab keymap.sh`
do ::

  update-rc.d  -f SERVICE remove