SAP Convergent Mediation ControlZone High Availability Cluster #

The following sections focus on background information and purpose of this document.

1.1 Abstract #

 

This guide describes configuration and basic testing of SUSE Linux Enterprise Server for SAP Applications 15 SP4 as a high availability cluster for Convergent Mediation (CM) ControlZone services.

From an application perspective, the following concept is covered:

• ControlZone platform and UI services are running together.

• ControlZone software is installed on central NFS.

• ControlZone software is copied to local disks of both nodes.

From an infrastructure perspective, the following concept is covered:

• Two-node cluster with disk-based SBD fencing

• Central NFS share statically mounted on both nodes

• On-premises deployment on physical and virtual machines

Despite the above menionted focus of this setup guide, other variants can be implemented as well. See Section 2, “Overview” below. The concept can also be used with newer service packs of SUSE Linux Enterprise Server for SAP Applications 15.

Note

This solution is supported only in the context of SAP RISE (https://www.sap.com/products/erp/rise.html).

The CM ControlZone platform is responsible for providing services to other instances. Several platform containers may exist in a CM system, for high availability, but only one is active at a time. The CM ControlZone UI is used to query, edit, import, and export data.

SUSE Linux Enterprise Server for SAP Applications is optimized in various ways for SAP applications. Particularly, it contains the SUSE Linux Enterprise High Availability cluster and specfic HA resource agents.

From the application perspective the following variants are covered:

From the infrastructure perspective the following variants are covered:

2.1 High availability for the Convergent Mediation ControlZone platform and UI #

 

The HA solution for CM ControlZone is a two-node active/passive cluster. A shared NFS file system is statically mounted by the operating system on both cluster nodes. This file system holds work directories. Client-side write caching needs to be disabled. The ControlZone software is installed into the central shared NFS, but is also copied to both nodes´ local file systems. The HA cluster uses the central directory for starting/stopping the ControlZone services. However, for monitoring the local copies of the installation are used.

The cluster can run monitor actions even when the NFS temporarily is blocked. Further, software upgrade is possible without downtime (rolling upgrade).

Figure 1: Two-node HA cluster and statically mounted file systems #

 

The ControlZone services platform and UI are handled as active/passive resources. The related virtual IP adress is managed by the HA cluster as well. A file system resource is configured for a bind-mount of the real NFS share. In case of file system failures, the cluster takes action. However, no mount or umount on the real NFS share is done.

All cluster resources are organized as one resource group. This results in a correct start/stop order and placement, while keeping the configuration simple.

Figure 2: ControlZone resource group #

 

See Section 5, “Integrating Convergent Mediation ControlZone with the Linux cluster” and manual page ocf_suse_SAPCMControlZone(7) for details.

2.2 Scope of this document #

 

For the SUSE Linux Enterprise High Availability two-node cluster described above, this guide explains how to:

• check basic settings of the two-node HA cluster with disk-based SBD.

• check basic capabilities of the ControlZone components on both nodes.

• configure an HA cluster for managing the ControlZone components platform and UI, together with related IP address.

• perform functional tests of the HA cluster and its resources.

• perform basic administrative tasks on the cluster resources.

Note

Neither installation of the basic SUSE Linux Enterprise High Availability cluster, nor installation of the CM ControlZone software is covered in the document at hand.

Consult the SUSE Linux Enterprise High Availability product documentation at https://documentation.suse.com/sle-ha/15-SP4/single-html/SLE-HA-administration/#part-install for installation instructions.

For Convergent Mediation installation instructions, refer to the respective product documentation at https://infozone.atlassian.net/wiki/spaces/MD9/pages/4849683/Installation+Instructions.

The ControlZone needs to be tested without the Linux cluster before integrating both. Each test needs to be done on both nodes.

# su - c11adm
~> echo $MZ_HOME $JAVA_HOME

/usr/sap/C11 /usr/lib64/jvm/jre-17-openjdk

~> which mzsh

/usr/sap/C11/bin/mzsh

~> echo "are you sure platform is not running on the other node?"

are you sure platform is not running on the other node?

~> mzsh startup -f platform

Starting platform...done.

~> mzsh status platform; echo $?

platform is running
0

~> mzsh startup -f ui

Starting ui...done.

~> mzsh status ui; echo $?

ui is running
0

~> mzsh shutdown ui

Shutting down ui....done.

~> mzsh status ui; echo $?

ui is not running
2

~> mzsh shutdown platform

Shutting down platform......done.

~> mzsh status platform; echo $?

platform is not running
2

# su - c11adm
~> export MZ_HOME="/opt/cm/C11"
~> export PATH="/opt/cm/C11/bin:$PATH"

~> echo $MZ_HOME $JAVA_HOME

/opt/cm/C11 /usr/lib64/jvm/jre-17-openjdk

~> which mzsh

/opt/cm/C11/bin/mzsh

~> mzsh status platform; echo $?

platform is running
0

~> mzsh status ui; echo $?

ui is running
0

HA clusters are complex, and the CM ControlZone is also complex. Deploying and running HA clusters for CM ControlZonen needs preparation, caution and care. Fortunately, most of the pitfalls and many best practices are already known. This chapter describes general administrative tasks.

# su - c11adm -c "mzsh status"
# crm_mon -1r
# crm configure show | grep cli-
# cibadmin -Q | grep fail-count
# cs_clusterstate -i

# watch -s8 cs_show_cluster_actions

# crm_mon -1r
# cs_wait_for_idle -s 5; crm resource start grp_cz_C11
# cs_wait_for_idle -s 5; crm_mon -1r

# crm_mon -1r
# cs_wait_for_idle -s 5; crm resource stop grp_cz_C11
# cs_wait_for_idle -s 5; crm_mon -1r

# su - c11adm -c "mzsh status"
# crm_mon -1r
# crm configure show | grep cli-
# cibadmin -Q | grep fail-count
# cs_clusterstate -i

# crm resource move grp_cz_C11 force
# cs_wait_for_idle -s 5; crm_mon -1r
# crm resource clear grp_cz_C11

# cs_wait_for_idle -s 5; crm_mon -1r
# crm configure show | grep cli-
# su - c11adm -c "mzsh status"

# su - c11adm -c "mzsh status"
# crm_mon -1r
# crm configure show | grep cli-
# cibadmin -Q | grep fail-count
# cs_clusterstate -i
# crm resource maintenance grp_cz_C11

# echo "PLEASE DO MAINTENANCE NOW"

# crm resource refresh grp_cz_C11
# cs_wait_for_idle -s 5; crm_mon -1r
# crm resource maintenance grp_cz_C11 off
# cs_wait_for_idle -s 5; crm_mon -1r
# su - c11adm -c "mzsh status"

# grep "SAPCMControlZone.*rc=[1-7,9]" /var/log/messages

# crm resource cleanup grp_cz_C11
# cibadmin -Q | grep fail-count

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