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10. Configuration Recap

10.1. Final Cluster Configuration

Note

Because of an open CentOS bug [https://bugs.centos.org/view.php?id=16939], installing dlm is not trivial. This chapter will be updated once the bug is resolved.

[root@pcmk-1 ~]# pcs resource
 Master/Slave Set: WebDataClone [WebData]
     Masters: [ pcmk-1 pcmk-2 ]
 Clone Set: dlm-clone [dlm]
     Started: [ pcmk-1 pcmk-2 ]
 ClusterIP  (ocf::heartbeat:IPaddr2):       Started pcmk-1
 Clone Set: WebFS-clone [WebFS]
     Started: [ pcmk-1 pcmk-2 ]
 WebSite    (ocf::heartbeat:apache):        Started pcmk-1

[root@pcmk-1 ~]# pcs resource op defaults
timeout: 240s

[root@pcmk-1 ~]# pcs stonith
  * my_stonith      (stonith:fence_virt):   Started pcmk-1

[root@pcmk-1 ~]# pcs constraint
Location Constraints:
Ordering Constraints:
  start ClusterIP then start WebSite (kind:Mandatory)
  promote WebDataClone then start WebFS-clone (kind:Mandatory)
  start WebFS-clone then start WebSite (kind:Mandatory)
  start dlm-clone then start WebFS-clone (kind:Mandatory)
Colocation Constraints:
  WebSite with ClusterIP (score:INFINITY)
  WebFS-clone with WebDataClone (score:INFINITY) (with-rsc-role:Master)
  WebSite with WebFS-clone (score:INFINITY)
  WebFS-clone with dlm-clone (score:INFINITY)
Ticket Constraints:

[root@pcmk-1 ~]# pcs status
Cluster name: mycluster
Stack: corosync
Current DC: pcmk-1 (version 1.1.18-11.el7_5.3-2b07d5c5a9) - partition with quorum
Last updated: Tue Sep 11 10:41:53 2018
Last change: Tue Sep 11 10:40:16 2018 by root via cibadmin on pcmk-1

2 nodes configured
11 resources configured

Online: [ pcmk-1 pcmk-2 ]

Full list of resources:

 my_stonith   (stonith:fence_virt):        Started pcmk-1
 Master/Slave Set: WebDataClone [WebData]
     Masters: [ pcmk-1 pcmk-2 ]
 Clone Set: dlm-clone [dlm]
     Started: [ pcmk-1 pcmk-2 ]
 ClusterIP  (ocf::heartbeat:IPaddr2):       Started pcmk-1
 Clone Set: WebFS-clone [WebFS]
     Started: [ pcmk-1 pcmk-2 ]
 WebSite    (ocf::heartbeat:apache):        Started pcmk-1

Daemon Status:
  corosync: active/disabled
  pacemaker: active/disabled
  pcsd: active/enabled

[root@pcmk-1 ~]# pcs cluster cib --config

<configuration>
  <crm_config>
    <cluster_property_set id="cib-bootstrap-options">
      <nvpair id="cib-bootstrap-options-have-watchdog" name="have-watchdog" value="false"/>
      <nvpair id="cib-bootstrap-options-dc-version" name="dc-version" value="1.1.18-11.el7_5.3-2b07d5c5a9"/>
      <nvpair id="cib-bootstrap-options-cluster-infrastructure" name="cluster-infrastructure" value="corosync"/>
      <nvpair id="cib-bootstrap-options-cluster-name" name="cluster-name" value="mycluster"/>
      <nvpair id="cib-bootstrap-options-stonith-enabled" name="stonith-enabled" value="true"/>
      <nvpair id="cib-bootstrap-options-last-lrm-refresh" name="last-lrm-refresh" value="1536679009"/>
    </cluster_property_set>
  </crm_config>
  <nodes>
    <node id="1" uname="pcmk-1"/>
    <node id="2" uname="pcmk-2"/>
  </nodes>
  <resources>
    <primitive class="stonith" id="impi-fencing" type="fence_ipmilan">
      <instance_attributes id="impi-fencing-instance_attributes">
        <nvpair id="impi-fencing-instance_attributes-pcmk_host_list" name="pcmk_host_list" value="pcmk-1 pcmk-2"/>
        <nvpair id="impi-fencing-instance_attributes-ipaddr" name="ipaddr" value="10.0.0.1"/>
        <nvpair id="impi-fencing-instance_attributes-login" name="login" value="testuser"/>
        <nvpair id="impi-fencing-instance_attributes-passwd" name="passwd" value="acd123"/>
      </instance_attributes>
      <operations>
        <op id="impi-fencing-interval-60s" interval="60s" name="monitor"/>
      </operations>
    </primitive>
    <clone id="WebDataClone">
      <primitive class="ocf" id="WebData" provider="linbit" type="drbd">
        <instance_attributes id="WebData-instance_attributes">
          <nvpair id="WebData-instance_attributes-drbd_resource" name="drbd_resource" value="wwwdata"/>
        </instance_attributes>
        <operations>
          <op id="WebData-demote-interval-0s" interval="0s" name="demote" timeout="90"/>
          <op id="WebData-monitor-interval-60s" interval="60s" name="monitor"/>
          <op id="WebData-notify-interval-0s" interval="0s" name="notify" timeout="90"/>
          <op id="WebData-promote-interval-0s" interval="0s" name="promote" timeout="90"/>
          <op id="WebData-reload-interval-0s" interval="0s" name="reload" timeout="30"/>
          <op id="WebData-start-interval-0s" interval="0s" name="start" timeout="240"/>
          <op id="WebData-stop-interval-0s" interval="0s" name="stop" timeout="100"/>
        </operations>
      </primitive>
      <meta_attributes id="WebDataClone-meta_attributes">
        <nvpair id="WebDataClone-meta_attributes-promoted-node-max" name="promoted-node-max" value="1"/>
        <nvpair id="WebDataClone-meta_attributes-clone-max" name="clone-max" value="2"/>
        <nvpair id="WebDataClone-meta_attributes-notify" name="notify" value="true"/>
        <nvpair id="WebDataClone-meta_attributes-promoted-max" name="promoted-max" value="2"/>
        <nvpair id="WebDataClone-meta_attributes-clone-node-max" name="clone-node-max" value="1"/>
        <nvpair id="WebDataClone-meta_attributes-promoted" name="promotable" value="true"/>
      </meta_attributes>
    </clone>
    <clone id="dlm-clone">
      <primitive class="ocf" id="dlm" provider="pacemaker" type="controld">
        <operations>
          <op id="dlm-monitor-interval-60s" interval="60s" name="monitor"/>
          <op id="dlm-start-interval-0s" interval="0s" name="start" timeout="90"/>
          <op id="dlm-stop-interval-0s" interval="0s" name="stop" timeout="100"/>
        </operations>
      </primitive>
      <meta_attributes id="dlm-clone-meta_attributes">
        <nvpair id="dlm-clone-meta_attributes-clone-max" name="clone-max" value="2"/>
        <nvpair id="dlm-clone-meta_attributes-clone-node-max" name="clone-node-max" value="1"/>
      </meta_attributes>
    </clone>
    <primitive class="ocf" id="ClusterIP" provider="heartbeat" type="IPaddr2">
      <instance_attributes id="ClusterIP-instance_attributes">
        <nvpair id="ClusterIP-instance_attributes-cidr_netmask" name="cidr_netmask" value="24"/>
        <nvpair id="ClusterIP-instance_attributes-ip" name="ip" value="192.168.122.120"/>
        <nvpair id="ClusterIP-instance_attributes-clusterip_hash" name="clusterip_hash" value="sourceip"/>
      </instance_attributes>
      <operations>
        <op id="ClusterIP-monitor-interval-30s" interval="30s" name="monitor"/>
        <op id="ClusterIP-start-interval-0s" interval="0s" name="start" timeout="20s"/>
        <op id="ClusterIP-stop-interval-0s" interval="0s" name="stop" timeout="20s"/>
      </operations>
      <meta_attributes id="ClusterIP-meta_attributes">
        <nvpair id="ClusterIP-meta_attributes-resource-stickiness" name="resource-stickiness" value="0"/>
      </meta_attributes>
    </primitive>
    <clone id="WebFS-clone">
      <primitive class="ocf" id="WebFS" provider="heartbeat" type="Filesystem">
        <instance_attributes id="WebFS-instance_attributes">
          <nvpair id="WebFS-instance_attributes-device" name="device" value="/dev/drbd1"/>
          <nvpair id="WebFS-instance_attributes-directory" name="directory" value="/var/www/html"/>
          <nvpair id="WebFS-instance_attributes-fstype" name="fstype" value="gfs2"/>
        </instance_attributes>
        <operations>
          <op id="WebFS-monitor-interval-20" interval="20" name="monitor" timeout="40"/>
          <op id="WebFS-notify-interval-0s" interval="0s" name="notify" timeout="60"/>
          <op id="WebFS-start-interval-0s" interval="0s" name="start" timeout="60"/>
          <op id="WebFS-stop-interval-0s" interval="0s" name="stop" timeout="60"/>
        </operations>
      </primitive>
    </clone>
    <primitive class="ocf" id="WebSite" provider="heartbeat" type="apache">
      <instance_attributes id="WebSite-instance_attributes">
        <nvpair id="WebSite-instance_attributes-configfile" name="configfile" value="/etc/httpd/conf/httpd.conf"/>
        <nvpair id="WebSite-instance_attributes-statusurl" name="statusurl" value="http://localhost/server-status"/>
      </instance_attributes>
      <operations>
        <op id="WebSite-monitor-interval-1min" interval="1min" name="monitor"/>
        <op id="WebSite-start-interval-0s" interval="0s" name="start" timeout="40s"/>
        <op id="WebSite-stop-interval-0s" interval="0s" name="stop" timeout="60s"/>
      </operations>
    </primitive>
  </resources>
  <constraints>
    <rsc_colocation id="colocation-WebSite-ClusterIP-INFINITY" rsc="WebSite" score="INFINITY" with-rsc="ClusterIP"/>
    <rsc_order first="ClusterIP" first-action="start" id="order-ClusterIP-WebSite-mandatory" then="WebSite" then-action="start"/>
    <rsc_colocation id="colocation-WebFS-WebDataClone-INFINITY" rsc="WebFS-clone" score="INFINITY" with-rsc="WebDataClone" with-rsc-role="Master"/>
    <rsc_order first="WebDataClone" first-action="promote" id="order-WebDataClone-WebFS-mandatory" then="WebFS-clone" then-action="start"/>
    <rsc_colocation id="colocation-WebSite-WebFS-INFINITY" rsc="WebSite" score="INFINITY" with-rsc="WebFS-clone"/>
    <rsc_order first="WebFS-clone" first-action="start" id="order-WebFS-WebSite-mandatory" then="WebSite" then-action="start"/>
    <rsc_colocation id="colocation-WebFS-dlm-clone-INFINITY" rsc="WebFS-clone" score="INFINITY" with-rsc="dlm-clone"/>
    <rsc_order first="dlm-clone" first-action="start" id="order-dlm-clone-WebFS-mandatory" then="WebFS-clone" then-action="start"/>
  </constraints>
  <rsc_defaults>
    <meta_attributes id="rsc_defaults-options">
      <nvpair id="rsc_defaults-options-resource-stickiness" name="resource-stickiness" value="100"/>
    </meta_attributes>
  </rsc_defaults>
  <op_defaults>
    <meta_attributes id="op_defaults-options">
      <nvpair id="op_defaults-options-timeout" name="timeout" value="240s"/>
    </meta_attributes>
  </op_defaults>
</configuration>

10.2. Node List

[root@pcmk-1 ~]# pcs status nodes
Pacemaker Nodes:
 Online: pcmk-1 pcmk-2
 Standby:
 Maintenance:
 Offline:
Pacemaker Remote Nodes:
 Online:
 Standby:
 Maintenance:
 Offline:

10.3. Cluster Options

[root@pcmk-1 ~]# pcs property
Cluster Properties:
 cluster-infrastructure: corosync
 cluster-name: mycluster
 dc-version: 1.1.18-11.el7_5.3-2b07d5c5a9
 have-watchdog: false
 last-lrm-refresh: 1536679009
 stonith-enabled: true

The output shows state information automatically obtained about the cluster, including:

  • cluster-infrastructure - the cluster communications layer in use
  • cluster-name - the cluster name chosen by the administrator when the cluster was created
  • dc-version - the version (including upstream source-code hash) of Pacemaker used on the Designated Controller, which is the node elected to determine what actions are needed when events occur

The output also shows options set by the administrator that control the way the cluster operates, including:

  • stonith-enabled=true - whether the cluster is allowed to use STONITH resources

10.4. Resources

10.4.1. Default Options

[root@pcmk-1 ~]# pcs resource defaults
resource-stickiness: 100

This shows cluster option defaults that apply to every resource that does not explicitly set the option itself. Above:

  • resource-stickiness - Specify the aversion to moving healthy resources to other machines

10.4.2. Fencing

[root@pcmk-1 ~]# pcs stonith show
  * my_stonith      (stonith:fence_virt):   Started pcmk-1
[root@pcmk-1 ~]# pcs stonith show my_stonith
 Resource: my_stonith (class=stonith type=fence_virt)
  Attributes: ipaddr="10.0.0.1" login="testuser" passwd="acd123" pcmk_host_list="pcmk-1 pcmk-2"
  Operations: monitor interval=60s (fence-monitor-interval-60s)

10.4.3. Service Address

Users of the services provided by the cluster require an unchanging address with which to access it.

[root@pcmk-1 ~]# pcs resource show ClusterIP
Resource: ClusterIP (class=ocf provider=heartbeat type=IPaddr2)
 Attributes: cidr_netmask=24 ip=192.168.122.120 clusterip_hash=sourceip
 Meta Attrs: resource-stickiness=0
 Operations: monitor interval=30s (ClusterIP-monitor-interval-30s)
             start interval=0s timeout=20s (ClusterIP-start-interval-0s)
             stop interval=0s timeout=20s (ClusterIP-stop-interval-0s)

10.4.4. DRBD - Shared Storage

Here, we define the DRBD service and specify which DRBD resource (from /etc/drbd.d/*.res) it should manage. We make it a promotable clone resource and, in order to have an active/active setup, allow both instances to be promoted at the same time. We also set the notify option so that the cluster will tell DRBD agent when its peer changes state.

[root@pcmk-1 ~]# pcs resource show WebDataClone
 Clone: WebDataClone (promotable)
  Meta Attrs: promoted-node-max=1 clone-max=2 notify=true promoted-max=2 clone-node-max=1
  Resource: WebData (class=ocf provider=linbit type=drbd)
   Attributes: drbd_resource=wwwdata
   Operations: demote interval=0s timeout=90 (WebData-demote-interval-0s)
               monitor interval=60s (WebData-monitor-interval-60s)
               notify interval=0s timeout=90 (WebData-notify-interval-0s)
               promote interval=0s timeout=90 (WebData-promote-interval-0s)
               reload interval=0s timeout=30 (WebData-reload-interval-0s)
               start interval=0s timeout=240 (WebData-start-interval-0s)
               stop interval=0s timeout=100 (WebData-stop-interval-0s)
[root@pcmk-1 ~]# pcs constraint ref WebDataClone
Resource: WebDataClone
  colocation-WebFS-WebDataClone-INFINITY
  order-WebDataClone-WebFS-mandatory

10.4.5. Cluster Filesystem

The cluster filesystem ensures that files are read and written correctly. We need to specify the block device (provided by DRBD), where we want it mounted and that we are using GFS2. Again, it is a clone because it is intended to be active on both nodes. The additional constraints ensure that it can only be started on nodes with active DLM and DRBD instances.

[root@pcmk-1 ~]# pcs resource show WebFS-clone
 Clone: WebFS-clone
  Resource: WebFS (class=ocf provider=heartbeat type=Filesystem)
   Attributes: device=/dev/drbd1 directory=/var/www/html fstype=gfs2
   Operations: monitor interval=20 timeout=40 (WebFS-monitor-interval-20)
               notify interval=0s timeout=60 (WebFS-notify-interval-0s)
               start interval=0s timeout=60 (WebFS-start-interval-0s)
               stop interval=0s timeout=60 (WebFS-stop-interval-0s)
[root@pcmk-1 ~]# pcs constraint ref WebFS-clone
Resource: WebFS-clone
  colocation-WebFS-WebDataClone-INFINITY
  colocation-WebSite-WebFS-INFINITY
  colocation-WebFS-dlm-clone-INFINITY
  order-WebDataClone-WebFS-mandatory
  order-WebFS-WebSite-mandatory
  order-dlm-clone-WebFS-mandatory

10.4.6. Apache

Lastly, we have the actual service, Apache. We need only tell the cluster where to find its main configuration file and restrict it to running on a node that has the required filesystem mounted and the IP address active.

[root@pcmk-1 ~]# pcs resource show WebSite
Resource: WebSite (class=ocf provider=heartbeat type=apache)
 Attributes: configfile=/etc/httpd/conf/httpd.conf statusurl=http://localhost/server-status
 Operations: monitor interval=1min (WebSite-monitor-interval-1min)
             start interval=0s timeout=40s (WebSite-start-interval-0s)
             stop interval=0s timeout=60s (WebSite-stop-interval-0s)
[root@pcmk-1 ~]# pcs constraint ref WebSite
Resource: WebSite
  colocation-WebSite-ClusterIP-INFINITY
  colocation-WebSite-WebFS-INFINITY
  order-ClusterIP-WebSite-mandatory
  order-WebFS-WebSite-mandatory
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