Chapter 6. Maintenance procedures
The following sections describe the recommended procedures to perform maintenance on HA cluster setups used for managing HANA Scale-Out System Replication. You must use these procedures independently from each other.
It is not necessary to put the cluster in maintenance-mode when using these procedures. For more information, refer to When to use "maintenance-mode" in RHEL High Availability Add-on for pacemaker based cluster?.
6.1. Updating the OS and HA cluster components
Please refer to Recommended Practices for Applying Software Updates to a RHEL High Availability or Resilient Storage Cluster, for more information.
6.2. Updating the SAP HANA instances
Procedure
If the HA cluster configuration described in this document manages the SAP HANA System Replication setup, then you need to execute some additional steps apart from the actual process of updating the SAP HANA instances before and after the update. Execute the following steps:
Put the
SAPHanaresource in unmanaged mode:[root]# pcs resource unmanage SAPHana_RH1_HDB10-clone- Update the SAP HANA instances using the procedure that SAP provides.
Refresh the status of the
SAPHanaresource to make sure the cluster is aware of the current state of the SAP HANA System Replication setup when the update of the SAP HANA instances has been completed and it has been verified that SAP HANA System Replication is working again:[root]# pcs resource refresh SAPHana_RH1_HDB10-clonePut the
SAPHanaresource back into managed mode so that the HA cluster will be able to react to any issues in the SAP HANA System Replication setup again when the HA cluster correctly picks up the current status of the SAP HANA System Replication setup:[root]# pcs resource manage SAPHana_RH1_HDB10-clone
6.3. Moving SAPHana resource to another node (SAP HANA System Replication takeover by HA cluster) manually
Move the promotable clone resource to trigger a manual takeover of SAP HANA System Replication:
[root]# pcs resource move SAPHana_RH1_HDB10-clone
pcs-0.10.8-1.el8 or later is required for this command to work correctly. For more information, refer to The pcs resource move command fails for a promotable clone unless "--master" is specified.
With each pcs resource move command invocation, the HA cluster creates a location constraint to cause the resource to move. For more information, refer to Is there a way to manage constraints when running pcs resource move?.
This constraint must be removed after it has been verified that the SAP HANA System Replication takeover has been completed in order to allow the HA cluster to manage the former primary SAP HANA instance again.
To remove the constraint created by pcs resource move, use the following command:
[root]# pcs resource clear SAPHana_RH1_HDB10-clone
What happens to the former SAP HANA primary instance after the takeover has been completed and the constraint has been removed depends on the setting of the AUTOMATED_REGISTER parameter of the SAPHana resource:
-
If
Automated_REGISTER=true, then the former SAP HANA primary instance is registered as the new secondary, and SAP HANA System Replication becomes active again. -
If
AUTOMATED_REGISTER=false, then it is up to the operator to decide what should happen with the former SAP HANA primary instance after the takeover.
