====== Cluster LVM ======
sources:

[[https://www.suse.com/documentation/sle_ha/book_sleha/data/sec_ha_clvm_config.html]]

[[https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Cluster_Administration/s1-admin-manage-nodes-delete-add-cli-CA.html]]

[[https://www.ibm.com/developerworks/community/blogs/mhhaque/resource/RHCS_IBM_POWER.pdf?lang=zh]]
===== Installation (Debian Jessie) =====
  - install necessary packages:<code bash>
apt-get install clvm cman</code>
  - edit /etc/lvm/lmv.conf, set:<code bash>
mirror_logs_require_separate_pvs = 1
locking_type = 3
</code>
  - set no wait time for quorum:<code bash>echo "CMAN_QUORUM_TIMEOUT=0" >> /etc/default/cman</code>
  - create config file /etc/cluster/cluster.conf and put it to all nodes:<code xml>
<cluster name="mycluster" config_version="1">
   <clusternodes>
     <clusternode name="10.0.0.23" nodeid="1">
         <fence>
         </fence>
     </clusternode>
     <clusternode name="10.0.0.112" nodeid="2">
         <fence>
         </fence>
     </clusternode>
   </clusternodes>
   <fencedevices>
   </fencedevices>
   <rm>
   </rm>
</cluster>
</code>
  - start cman service and clvm service on all nodes:<code bash>
service cman start
service clvm start
</code>
  - check that nodes are online in cluster:<code bash>
cman_tool nodes</code>output should be:<code bash>
root@debian:~# cman_tool nodes
Node  Sts   Inc   Joined               Name
   1   M      4   2015-10-30 09:34:43  10.0.0.23
   2   M      8   2015-10-30 09:36:04  10.0.0.112
</code>
  - assuming that /dev/sdb and /dev/sdc are volumes exported from SANs
  - create physical volumes:<code bash>
pvcreate /dev/sdb
pvcreate /dev/sdc</code>
  - create clustered volume group:<code bash>
vgcreate --clustered y guma_cerna /dev/sdb /dev/sdc</code>
  - create mirrored lvm:<code bash>
lvcreate -n testovaci_lv -m1 -L 1.0g guma_cerna --nosync</code>(--nosync means that data will not be synced upon creating - since the lv should not contain any data upon its creating its OK)
  - (optional) check that the volume were created succesfully on both SANs:<code bash>
lvs -a -o +devices</code>

===== Adding/deleting node from cluster =====
  - If deleting stop all cluster services on node e.g.:<code bash>
service stop clvm
service stop cman</code>
  - install cman clvm on new node(s) - don't forget to setup the /etc/lvm/lvm.conf file
  - attach SANs on new node(s)
  - edit the /etc/cluster/cluster.conf and increase serial:<code xml>
<cluster name="mycluster" config_version="2">
   <clusternodes>
     <clusternode name="10.0.0.23" nodeid="1">
         <fence>
         </fence>
     </clusternode>
     <clusternode name="10.0.0.112" nodeid="2">
         <fence>
         </fence>
     </clusternode>
     <clusternode name="10.0.0.110" nodeid="3">
         <fence>
         </fence>
     </clusternode>
  </clusternodes>
   <fencedevices>
   </fencedevices>
   <rm>
   </rm>
</cluster></code>
  - distribute the file to ALL nodes in cluster and issue following command from any node:<code bash>cman_tool version -r -S</code>
  - to use previously created volumes those must be activated on new node:<code bash>
lvchange -a y /dev/guma_cerna/testovaci_lv</code>
===== Removing node from the cluster =====
  - stop all cluster services and then stop cman service with parameter leave<code bash>
service clvm stop
service cman stop leave
</code>