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The idea is simple:

Install a vserver on a DRBD resource and let it failover to the other node of a cluster.

This configuration uses vserver, DRBD and heartbeat. This page will not describe, how these packages are installed and configured. Only the important topics are mentioned.

Steps of installation:

In detail

Prepare the disk space:

You will need some block device like /dev/hdaX, or a better choice is to use LVM.

lvcreate -L3000 -nlvvs03 vg0

A recommended method is, to have DRBD metadata on an extra block device for each DRBD device.

Prepare space for it:

lvcreate -L132 -nlvvs03md vg0

Create an entry in /etc/drbd.conf using your favorite editor:

resource vs03 {
  protocol C;
  incon-degr-cmd "echo '!DRBD! pri on incon-degr' | wall ; sleep 60 ; halt -f";

  startup {
    wfc-timeout  100;
    degr-wfc-timeout 120;    # 2 minutes.
  }

  disk {
    on-io-error   pass_on;
  }

  net {
    # sndbuf-size 512k;
    # timeout       60;    #  6 seconds  (unit = 0.1 seconds)
    # connect-int   10;    # 10 seconds  (unit = 1 second)
    # ping-int      10;    # 10 seconds  (unit = 1 second)
    # max-buffers     2048;
    # max-epoch-size  2048;
    # ko-count 4;
    # on-disconnect reconnect;
  }

  syncer {
    rate 10M;
    group 1;
    al-extents 257;
  }

  on cel600 {
    device     /dev/drbd1;
    disk       /dev/vg0/lvvs03;
    address    192.168.0.22:7789;
    meta-disk  /dev/vg0/lvvs03md[0];
  }

  on xp2400 {
    device    /dev/drbd1;
    disk      /dev/vg0/lvvs03;
    address   192.168.0.21:7789;
    meta-disk /dev/vg0/lvvs03md[0];
  }
}

Start DRBD

/etc/init.d/drbd start

The DRBD resource is in an undefined state. It needs to be forced to be 'primary' on the current node.

drbdsetup /dev/drbd1 primary --do-what-I-say

Obviously a filesystem is needed on top of DRBD:

mke2fs -j /dev/drbd1

Also we need a mount point somewhere:

mkdir /mnt/vs03

As heartbeat is intended to manage the vserver, using the heartbeat script for mounting is a first test:

/etc/ha.d/resource.d/Filesystem /dev/drbd1 /mnt/vs03 ext3 start

There are many methods how to install a vserver. Here 'debootstrap' is used. The important option is '--rootdir' to force the installation to the DRBD device.

vserver -v vs03 build --force --rootdir /mnt/vs03 \
-m debootstrap --hostname vs03.nack.at \
--netdev eth0 --interface 192.168.0.3/24 --context 3 -- \
-d sarge -m http://ftp.at.debian.org/debian/

We could start the vserver now. But first we try to make the configuration more pretty.

cd /mnt/vs03/vs03/etc/rc0.d
rm K20makedev K25hwclock.sh S30urandom S31umountnfs.sh  S35networking S36ifupdown S40umountfs S90halt K89klogd
cd ../rc6.d
rm K20makedev K25hwclock.sh S30urandom S31umountnfs.sh  S35networking S36ifupdown S40umountfs S90reboot K89klogd
cd ../rcS.d
rm S05keymap.sh S48console-screen.sh S50hwclock.sh S40networking  S45mountnfs.sh S10checkroot.sh S02mountvirtfs
rm S30procps.sh S35mountall.sh S36mountvirtfs S39ifupdown S30checkfs.sh S18ifupdown-clean S18hwclockfirst.sh
cd ../rc2.d
rm S20makedev S11klogd

If we want to have virtual IPs in the host context managed by heartbeat, there can be conflicts (and funny effects), if we do not 'name' the alias of the vserver IP.

echo vs03 > /etc/vservers/vs03/interfaces/0/name

sshd should only listen to the IPs of the host context:

xp2400:/# cat /etc/ssh/sshd_config | grep ListenAddress
ListenAddress 192.168.0.21:22
ListenAddress 192.168.0.20:22

After these checks it's time to start the vserver:

xp2400:/# vserver vs03 start

Check if the interface is nicely named and shown with ifconfig:

xp2400:/#  ip addr show
[...]
2: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 1000
    link/ether 00:30:bd:6b:d6:8f brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.21/24 brd 192.168.0.255 scope global eth0
    inet 192.168.0.3/24 brd 192.168.0.255 scope global secondary eth0:vs03
    inet6 fe80::230:bdff:fe6b:d68f/64 scope link
       valid_lft forever preferred_lft forever

xp2400:/# ifconfig
eth0      Link encap:Ethernet  [...]

eth1      [...]

eth0:vs03 Link encap:Ethernet  HWaddr 00:30:BD:6B:D6:8F
          inet addr:192.168.0.3  Bcast:192.168.0.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:177 Base address:0xd000

Enter the vserver:

xp2400:/# vserver vs03 enter

In the vserver we check the base configuration and install some packages.

vs03:/# base-config
vs03:/# apt-get update
vs03:/# apt-get install locales
vs03:/# apt-get install less
vs03:/# nano /etc/resolv.conf
vs03:/# ping www.linux-vserver.org

We want to install at least one service, sshd. 

vs03:/# apt-get install ssh
vs03:/# nano /etc/ssh/sshd_config
vs03:/# cat /etc/ssh/sshd_config | grep ListenAddress
ListenAddress 192.168.0.3:22
vs03:/# /etc/init.d/ssh restart
Restarting OpenBSD Secure Shell server: sshd.
vs03:/# passwd
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
vs03:/# exit
logout

Test the ssh login:

xp2400:/# ssh root@192.168.0.3
The authenticity of host '192.168.0.3 (192.168.0.3)' can't be established.
RSA key fingerprint is e2:19:d1:8d:7f:ac:0a:ce:12:f5:06:b7:ae:41:96:59.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.0.3' (RSA) to the list of known hosts.
Password: <secret>
vs03:~#

The configuration on one node is ready.

To be continued ...