View source for XEN with live migration with Pacemaker and DRBD

'''On both members of the cluster'''

* /etc/modprobe.conf
 options drbd disable_sendpage=1
* /etc/lvm/lvm.conf
 filter = [ "r|/dev/cdrom|", "r|/dev/drbd.*|" ]
* create logical volume
 lvcreate --size 320G --name vsvn vg1
* /etc/drbd.conf
Make sure device name and port numbers are unique
<pre>
resource vsvn {
  net {
    allow-two-primaries;
  }
  on xen-11.dev.videonext.net {
    device    /dev/drbd2;
    disk      /dev/vg1/vsvn;
    address   10.0.0.1:7787;
    flexible-meta-disk internal;
  }
  on xen-12.dev.videonext.net {
    device    /dev/drbd2;
    disk      /dev/vg1/vsvn;
    address   10.0.0.2:7787;
    flexible-meta-disk internal;
  }
}
</pre>
* Create drbd device
 drbdadm create-md vsvn
* Bring it up
 drbdadm up vsvn
* Make sure resource is in ''Connected'' state
<pre>
# cat /proc/drbd 
 2: cs:Connected ro:Secondary/Secondary ds:Inconsistent/Inconsistent C r----
    ns:0 nr:0 dw:0 dr:0 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:b oos:335534044
</pre>
* initialize meta-data (run this command on one of the servers)
  drbdadm -- --clear-bitmap new-current-uuid vsvn
* Make sure resource is ''UpToDate''
<pre>
# cat /proc/drbd 
 2: cs:Connected ro:Secondary/Secondary ds:UpToDate/UpToDate C r----
    ns:0 nr:0 dw:0 dr:0 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:b oos:0
</pre>
* Make resource is primary on one of the host, where you intend to run installation process
 drbdadm primary vsvn

* install VM, for example
<pre>
virt-install --name vsvn --ram=512 --vcpus=1 -p --disk=path=/dev/drbd/by-res/vsvn \
--nographics --location=http://ftp.videonext.net/private/CentOS/5.4/x86_64/os \
--extra-args="noipv6 headless clocksource=jiffies dhcpclass=intserver ks=http://noc.videonext.net/cfg/vsvn.cfg"
</pre>

* After installation complete

Make sure you have copies of you new initrd and vmlinuz in /xen/, they can be shared between different VM, but proper kernel version number needs to be installed in VM as well, if not just scp /boot/initrd* and /boot/vmlinuz* from VM to xen-11:/xen/

* Shutdown VM 
 xm shutdown vsvn

* Create configuration file xen-11, it will be propagated to xen-12 via rsync automatically
 cp /etc/xen/vsvn /xen/vsvn.cfg
 vi /xen/vsvn.cfg

replace bootloader with kernel,ramdisk,extra; modify disk definition to use drbd block device
 cat /xen/vsvn.cfg

<pre>
name = "vsvn"
uuid = "73ff1420-cc5e-ebfc-9046-b25e5e6b5b6f"
maxmem = 512
memory = 512
vcpus = 1
kernel = "/xen/vmlinuz-2.6.18-164.15.1.el5xen"
ramdisk = "/xen/initrd-2.6.18-164.15.1.el5xen.img"
extra = "ro root=/dev/xvda1 console=xvc0"
on_poweroff = "destroy"
on_reboot = "restart"
on_crash = "restart"
disk = [ "drbd:vsvn,xvda,w" ]
vif = [ "mac=00:16:36:4e:40:e1,bridge=xenbr0,script=vif-bridge" ]
</pre>

* make sure xen relocation is enabled
<pre>
grep ^\(xend-relocation /etc/xen/xend-config.sxp 
(xend-relocation-server yes)
(xend-relocation-port 8002)
(xend-relocation-address '')
(xend-relocation-hosts-allow '')
</pre>

* create Pacemaker resource
<pre>
crm configure primitive xen_vsvn ocf:heartbeat:Xen \
params xmfile="/xen/vsvn.cfg" \
op start interval="0" timeout="60" \
op stop interval="0" timeout="300" \
op monitor start-delay="120" interval="60" timeout="30" \
meta allow-migrate="true"
</pre>

* Enjoy
 # crm resource show xen_vsvn
 resource xen_vsvn is running on: xen-12.dev.videonext.net