== How To Install Ganeti Clusters and Instances ==

=== suppositions ===

Suppose that there are two identical hosts: foo.debian.org and bar.debian.org.

They are running squeeze and have been integrated into Debian infrastructure.

They will serve as nodes in a ganeti cluster named foobar.debian.org.

They have a RAID1 array exposing three partitions: c0d0p1 for /, c0d0p2 for
swap and c0d0p3 for lvm volume groups to be used by ganeti via drbd.

They have two network interfaces: eth0 (public) and eth1 (private).

The public network is A.B.C.0/24 with gateway A.B.C.254.

The private network is E.F.G.0/24 with no gateway.

Suppose that the first instance to be hosted on foobar.debian.org is
qux.debian.org.

The following DNS records exist:

{{{
    foobar.debian.org.                  IN A   A.B.C.1
    foo.debian.org.                     IN A   A.B.C.2
    bar.debian.org.                     IN A   A.B.C.3
    qux.debian.org.                     IN A   A.B.C.4
    foo.debprivate-hoster.debian.org.   IN A   E.F.G.2
    bar.debprivate-hoster.debian.org.   IN A   E.F.G.3
}}}

=== install required packages ===

On each node, install the required packages:

{{{
    # maybe: apt-get install drbd-utils
    # maybe: apt-get install ganeti-instance-debootstrap
    apt-get install ganeti2 ganeti-htools qemu-kvm
}}}

=== configure kernel modules ===

On each node, ensure that the required kernel modules are loaded at boot:

{{{
    ainsl /etc/modules 'drbd minor_count=255 usermode_helper=/bin/true'
    ainsl /etc/modules 'hmac'
    ainsl /etc/modules 'tun'
    ainsl /etc/modules 'ext3'
    ainsl /etc/modules 'ext4'
}}}

=== configure networking ===

On each node, ensure that br0 (not eth0) and eth1 are configured.

The bridge interface, br0, is used by the guest virtual machines to reach the
public network.

If the guest virtual machines need to access the private network, then br1
should be configured rather than eth1.

To prevent the link address changing due to startup/shutdown of virtual
machines, explicitly set the value.

This is the interfaces file for foo.debian.org:

{{{
    auto br0
    iface br0 inet static
      bridge_ports eth0
      bridge_maxwait 0
      bridge_fd 0
      address A.B.C.2
      netmask 255.255.255.0
      gateway A.B.C.254
      up ip link set addr $(cat /sys/class/net/$IFACE/address) dev $IFACE

    auto eth1
    iface eth1 inet static
      address E.F.G.2
      netmask 255.255.255.0
}}}

This is the interfaces file for bar.debian.org:

{{{
    auto br0
    iface br0 inet static
      bridge_ports eth0
      bridge_maxwait 0
      bridge_fd 0
      address A.B.C.3
      netmask 255.255.255.0
      gateway A.B.C.254
      up ip link set addr $(cat /sys/class/net/$IFACE/address) dev $IFACE

    auto eth1
    iface eth1 inet static
      address E.F.G.3
      netmask 255.255.255.0
}}}

=== configure lvm ===

On each node, configure lvm to ignore drbd devices and to prefer
{{{/dev/cciss}}} devices names over {{{/dev/block}}} device names
([[http://code.google.com/p/ganeti/issues/detail?id=93|why?]]):

{{{
    ssed -i \
      -e 's#^\(\s*filter\s\).*#\1= [ "a|.*|", "r|/dev/drbd[0-9]+|" ]#' \
      -e 's#^\(\s*preferred_names\s\).*#\1= [ "^/dev/dm-*/", "^/dev/cciss/" ]#' \
      /etc/lvm/lvm.conf
    service lvm2 restart
}}}

=== create lvm volume groups ===

On each node, create a volume group:

{{{
    vgcreate vg_ganeti /dev/cciss/c0d0p3
}}}

=== exchange ssh keys ===

on each node:

{{{
   mkdir -m 0700 -p /root/.ssh &&
   ln -s /etc/ssh/ssh_host_rsa_key /root/.ssh/id_rsa
}}}

=== configure iptables (via ferm) ===

the nodes must connect to each other over the public and private networks for a number of reasons; see the ganeti2 module in puppet

=== instantiate the cluster ===

On the master node (foo) only:

{{{
    gnt-cluster init \
      --master-netdev br0 \
      --vg-name vg_ganeti \
      --secondary-ip E.F.G.2 \
      --enabled-hypervisors kvm \
      --nic-parameters link=br0 \
      --mac-prefix 00:16:37 \
      --no-ssh-init \
      --no-etc-hosts \
      --hypervisor-parameters kvm:initrd_path=,kernel_path= \
      foobar.debian.org
}}}

Note the following:

* the master network device is set to br0, matching the public network bridge interface created above
* the volume group is set to vg_ganeti, matching the volume group created above
* the secondary IP address is set to the value of the master node's interface on the private network
* the nic parameters for instances is set to use br0 as default bridge
* the MAC prefix is registered in the dsa-kvm git repo

=== add slave nodes ===

For each slave node (only bar for this example):

on the slave, append the master's /etc/ssh/ssh_host_rsa_key.pub to
/etc/ssh/userkeys/root.  This is only required temporarily - once
everything works, puppet will put it/keep it there.

on the master node (foo):

{{{
    gnt-node add \
      --secondary-ip E.F.G.3 \
      --no-ssh-key-check \
      --no-node-setup \
      bar.debian.org
}}}

more stuff:

{{{
  gnt-cluster modify --reserved-lvs='vg0/local-swap.*'
  maybe: gnt-cluster modify --nic-parameters mode=openvswitch
}}}

Note the following:

* the secondary IP address is set to the value of the slave node's interface on the private network

=== verify cluster ===

On the master node (foo):

{{{
    gnt-cluster verify
}}}

If everything has been configured correctly, no errors should be reported.

=== create the 'noop' variant ===

Ensure that the ganeti-os-noop is installed.

----

== How To Install Ganeti Instances ==

Suppose that qux.debian.org will be an instance (a virtual machine) hosted on
the foobar.debian.org ganeti cluster.

Before adding the instance, an LDAP entry must be created so that an A record
for the instance (A.B.C.4) exists.

=== create the instance ===

On the master node (foo):

{{{
    gnt-instance add \
      --node foo:bar \
      --disk-template drbd \
      --os-size 4GiB \
      --os-type debootstrap+dsa \
      --hypervisor-parameters kvm:initrd_path=,kernel_path= \
      --net 0:ip=A.B.C.4 \
      qux.debian.org
}}}

Note the following:

* the primary and secondary nodes have been explicitly set
* the operating system type is 'debootstrap+dsa'
* the network interfarce 0 (eth0 on the system) is set to the instance's interface on the public network
* If qux.d.o does not yet exist in DNS/LDAP, you may need --no-ip-check --no-name-check.  Be careful that the hostname and IP address are not taken already!

----

== Variations ==

If the instances require access to the private network, then there are two modifications necessary.

=== re-configure networking ===

On the nodes, ensure that br1 is configured (rather than eth1).

This is the interfaces file for foo.debian.org:

{{{
    auto br0
    iface br0 inet static
      bridge_ports eth0
      bridge_maxwait 0
      bridge_fd 0
      address A.B.C.2
      netmask 255.255.255.0
      gateway A.B.C.254
      up ip link set addr $(cat /sys/class/net/$IFACE/address) dev $IFACE

    auto br1
    iface br1 inet static
      bridge_ports eth1
      bridge_maxwait 0
      bridge_fd 0
      address E.F.G.2
      netmask 255.255.255.0
      up ip link set addr $(cat /sys/class/net/$IFACE/address) dev $IFACE
}}}

This is the interfaces file for bar.debian.org:

{{{
    auto br0
    iface br0 inet static
      bridge_ports eth0
      bridge_maxwait 0
      bridge_fd 0
      address A.B.C.3
      netmask 255.255.255.0
      gateway A.B.C.254
      up ip link set addr $(cat /sys/class/net/$IFACE/address) dev $IFACE

    auto br1
    iface br1 inet static
      bridge_ports eth1
      bridge_maxwait 0
      bridge_fd 0
      address E.F.G.3
      netmask 255.255.255.0
      up ip link set addr $(cat /sys/class/net/$IFACE/address) dev $IFACE
}}}

=== create or update the instance  ===

When creating the instance, indicate both networks:

{{{
    gnt-instance add \
      --node foo:bar \
      --disk-template drbd \
      --os-size 4GiB \
      --os-type debootstrap+dsa \
      --hypervisor-parameters kvm:initrd_path=,kernel_path= \
      --net 0:ip=A.B.C.4 \
      --net 1:link=br1,ip=E.F.G.4 \
      qux.debian.org
}}}

* If qux.d.o does not yet exist in DNS/LDAP, you may need --no-ip-check --no-name-check.  Be careful that the hostname and IP address are not taken already!

When updating an existing instance, add the interface:

{{{
    gnt-instance shutdown qux.debian.org
    gnt-instance modify \
      --net add:link=br1,ip=E.F.G.4 \
      qux.debian.org
    gnt-instance startup qux.debian.org
}}}

Please note that the hook scripts are run only at instance instantiation.  When
adding interfaces to an instance, the guest opearting system must be updated
manually.


* If you are importing an instance from libvirt with LVM setup, you can adopt LVs:

{{{
    gnt-instance add -t plain --os-type debootstrap+dsa-wheezy \
      --disk 0:adopt=lully-boot \
      --disk 1:adopt=lully-root \
      --disk 2:adopt=lully-swap \
      --disk 3:adopt=lully-log  \
      --hypervisor-parameters kvm:initrd_path=,kernel_path= \
      --net 0:ip=82.195.75.99 -n clementi.debian.org  lully.debian.org
}}}

And you want to convert it to use DRBD afterwards and start it on the other cluster node, so we can ensure that DRBD is correctly working.
{{{
    gnt-instance shutdown lully.debian.org
    gnt-instance modify -t drbd -n czerny.debian.org lully.debian.org
    gnt-instance failover lully.debian.org
    gnt-instance startup lully.debian.org
}}}

* Some instances NEED ide instead of virtio

{{{
    gnt-instance modify --hypervisor-parameters disk_type=ide fils.debian.org
}}}

* To import instances with SAN volumes

{{{
    gnt-instance add -t blockdev --os-type debootstrap+dsa \
      --disk 0:adopt=/dev/disk/by-id/scsi-reger-boot \
      --disk 1:adopt=/dev/disk/by-id/scsi-reger-root \
      --hypervisor-parameters kvm:initrd_path=,kernel_path= \
      --net 0:ip=206.12.19.124 -n rossini.debian.org reger.debian.org
}}}

* How to add new LUNs to Bytemark Cluster

** Add new LUN to MSA and export to all blades

{{{
  Log into MSA controller

  Choose which vdisk to use, use "show vdisks" to list

Add the volume:
  # create volume vdisk msa2k-2-500gr10 size 5G donizetti

Find a free LUN:

  # show lun-maps
  or (if we assume they are all the same)
  # show host-maps 3001438001287090

Make a note of the next free LUN

Generate map commands for all blades, all ports, run locally:

  $ for bl in 1 2 3 4 5 6 ; do for p in 1 2 3 4; do echo "map volume donizetti lun 27 host bm-bl$bl-p$p" ; done ; done

Paste the output into the MSA shell

Find the WWN by doing show host-maps and looking for the volume name.
Transform it using the sed run at the top of /etc/multipath.conf:

echo "$WWN" | sed -re 's#(.{6})(.{6})0000(.{2})(.*)#36\1000\2\3\4#'
}}}

{{{

  then:
  gnt-cluster command "echo 1 > /sys/bus/pci/devices/0000:0e:00.0/cciss0/rescan"
  
  then:
  reload multipath-tools on gnt-master (normaly bm-bl1):
  service multipath-tools reload
  add the WWNs to dsa-puppet/modules/multipath/files/multipath-bm.conf and define the alias and commit that file to git.

  then:
  gnt-cluster command "puppet agent -t"

  This will update the multipath config on all cluster nodes. WITHOUT doing this, you can't migrate VMs between nodes.
}}}

** Remove LUNs.

Order is important, or else things get very, very confused and the world needs a reboot.

*** Make sure nothing uses the volume anymore.

*** Make sure we do not have any partitions lying around for it:
{{{
  gnt-cluster command "ls -l /dev/mapper/backuphost*"
  # and maybe:
  gnt-cluster command "kpartx -v -p -part -d /dev/mapper/backuphost"
}}}

*** flush the device, remove the multipath mapping, flush all backing devices:
{{{
  root@bm-bl1:~# cat flush-mp-device 
  #!/bin/sh

  dev="$1"

  if [ -z "$dev" ] || ! [ -e "$dev" ]; then
    echo 2>&1 "Device $dev does not exist."
    exit 1
  fi

  devs=$(multipath -ll "$dev" | grep cciss | sed -e 's/.*cciss!//; s/ .*//;')

  if [ -z "$devs" ]; then
    echo 2>&1 "No backends found for $dev."
    exit 1
  fi

  set -e

  blockdev --flushbufs "$dev"
  multipath -f "$dev"
  for d in $devs; do
    blockdev --flushbufs "/dev/cciss/$d"
  done
  echo done.
}}}
{{{
  gnt-cluster command "/root/flush-mp-device /dev/mapper/backuphost"
}}}

*** Immediately afterwards, paste the output of the following to the MSA console.  Best prepare this before, so you do it quickly before anything else rescans stuff, reloads or restarts multipathd, and the devices become used again.
{{{
  for bl in 1 2 3 4 5 6 ; do for p in 1 2 3 4; do echo "unmap volume DECOMMISSION-backuph host bm-bl$bl-p$p" ; done ; done
}}}

*** Lastly, rescan the scsi bus on all hosts.  Do not forget that.  hpacucli and the monitoring tools might lock up the machine if they try to check the status of a device that now no longer exists but that the system still thinkgs is around.
{{{
  gnt-cluster command "echo 1 > /sys/bus/pci/devices/0000:0e:00.0/cciss0/rescan"
}}}