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HA cluster configuration for SLES

Cluster installation

SLES for SAP images that are sold by Amazon through Amazon Marketplace come with pre-installed SUSE HAE packages. Ensure that you have the latest version of these packages. If required, update them by using the zypper command, as shown in the following example.

# zypper update
# reboot    

If you are using BYOS images, ensure that the following packages are installed:

Cluster configuration

System logging

SUSE recommends using the rsyslogd daemon for logging in the SUSE cluster. Install the rsyslog package as a root user on all cluster nodes. logd is a subsystem to log additional information coming from the STONITH agent.

# zypper install rsyslog
# systemctl enable logd
# systemctl start logd

Install SAP cluster connector.

On both the nodes, run the following command.

# zypper install sap-suse-cluster-connector

Add the following lines to the ASCS and ERS profile parameters.

service/halib = $(DIR_CT_RUN)/saphascriptco.so
service/halib_cluster_connector = /usr/bin/sap_suse_cluster_connector       

Add the sidadm user to the Linux haclient group.

# usermod -a -G haclient sidadm

Corosync configuration

The cluster services (pacemaker and corosync) should be in a stopped state when performing cluster configuration. Check the status and stop the pacemaker service if it is running.

Check the status

# systemctl status pacemaker

Stop the service

# systemctl stop pacemaker

Create encrypted keys

Run the following command to create a secret key, which is used to encrypt all of the cluster communication.

# corosync-keygen

The new authkey key file is created at /etc/corosync/. Copy this file to the same location on the second cluster node, with the same permissions and ownership.

hahost01:/etc/corosync # scp -p authkey root@hahost02:/etc/corosync

Create corosync configuration file

All cluster nodes are required to have a local configuration file named /etc/corosync/corosync.conf, as shown in the following example.

# Read the corosync.conf.5 manual page
totem {
  version: 2
  rrp_mode: passive
  token: 30000
  consensus: 36000
  token_retransmits_before_loss_const: 10
  max_messages: 20
  crypto_cipher: none
  crypto_hash: none
  clear_node_high_bit: yes
  interface {
    ringnumber: 0
    bindnetaddr: x.x.x.x
    mcastport: 5405
    ttl: 1
  }
  transport: udpu
}
 logging {
      fileline: off
      to_logfile: yes
      to_syslog: yes
      logfile: /var/log/cluster/corosync.log
      debug: off
      timestamp: on
      logger_subsys {
         subsys: QUORUM
         debug: off
     }
}
nodelist {
  node {
  ring0_addr: x.x.x.x
  ring1_addr: x.x.x.x
  nodeid: 1
  }
  node {
  ring0_addr: x.x.x.x
  ring1_addr: x.x.x.x
  nodeid: 2
  }
}

quorum {
  # Enable and configure quorum subsystem (default: off)
  # see also corosync.conf.5 and votequorum.5
  provider: corosync_votequorum
  expected_votes: 2
  two_node: 1
}    

Replace the values for the following variables with those of your environment:

The secondary ring corosync configuration provides redundancy. It enables the cluster nodes to communicate with each other in case of a communication issue with the primary IP address.

Update the hacluster password

Change the password for user hacluster on both nodes.

#passwd hacluster

Start the cluster

Start the cluster on both the primary and the secondary node, and then check the status.

Start the cluster by running the following command.

# systemctl start pacemaker

Check the status with the crm_mon-1 command, as shown in the following example. You will see that both nodes are online, and will see a full list of any resources that are available.

# crm_mon -1
Cluster Summary:
  * Stack: corosync
  * Current DC: hahost01 (version 2.0.xxxxxxxxxxx) - partition with quorum
  * Last updated: 
  * Last change:  by hacluster via crmd on hahost01
  * 2 nodes configured
  * 0 resource instances configured

Node List:
  * Online: [ hahost01 hahost02 ]

Active Resources:
  * No active resources
        

You can find the ring status and the associated IP address of the cluster with the corosync-cfgtool command, as shown in the following example.

# corosync-cfgtool –s
Printing ring status.
Local node ID 1
RING ID 0
        id      = x.x.x.x
        status  = ring 0 active with no faults
RING ID 1
        id      = x.x.x.x
        status  = ring 1 active with no faults