PowerHA SystemMirror for SAP HANA

The high availability concepts of SAP HANA reduce the downtime of a system in case of any software or hardware failures.

The SAP HANA high availability policy defines all SAP HANA components as resources and starts or stops them in a pre-defined sequence to provide high availability for your SAP HANA system. The SAP HANA components must be specified as an automated resource in the PowerHA® SystemMirror® by using Smart Assist.

The following components of the software stack in an SAP HANA installation must be highly available:
Primary and secondary host with the following processes on each host:
  • The hdbdaemon daemon manages the following subprocesses:
    • hdbindexserver
    • hdbnameserver
    • hdbxsengine
    • hdbwebdispatcher
    • hdbcompileserver
    • hdbpreprocessor
  • The sapstartsrv start, stop, and monitor processes for the hdbdaemon daemon.
  • IP address to access the primary host

PowerHA SystemMirror Version 7.2.3, or later, supports the SAP HANA Active/Active (read enabled) secondary configuration mode through Smart Assist. The Active/Active (read enabled) secondary configuration mode reduces the load on the primary system and extends read capabilities. In this mode, the primary system remains active and it supports read and write operations and the secondary system will be in the standby mode and it supports only the read operation.

When you specify the CONFIG=ACTIVE_ACTIVE parameter, PowerHA SystemMirror configures a secondary virtual IPv4 address for establishing a direct connection to the secondary system. PowerHA SystemMirror already supports a virtual IPv4 address, which is active on the primary system. When the secondary system is not available, PowerHA SystemMirror activates the secondary virtual IPv4 address along with the first virtual IPv4 address on the primary system.

start of changeIn PowerHA SystemMirror Version 7.2.3 for Linux with Service Pack 1, or later, you must specify the PREFER_TAKEOVER parameter when you configure SAP HANA through Smart Assist. The PREFER_TAKEOVER parameter defines whether PowerHA SystemMirror switch over the SAP HANA database to the secondary node when the primary SAP HANA instance fails instead of restarting the SAP HANA instance on the primary node locally. By default the value of the PREFER_TAKEOVER parameter is TRUE for the Performance Optimized and Active-Active SAP HANA configuration modes because switching over to another node in these configuration modes is faster than restarting the node locally. end of change

start of changePowerHA SystemMirror Version 7.2.3 for Linux with Service Pack 1, or later, supports the SAP HANA Cost Optimized configuration mode through Smart Assist. When you specify the CONFIG=COST_OPT parameter, the secondary node is used for a non-productive SAP HANA and the secondary node must limit usage of system resources. The table preload for productive SAP HANA is turned off. Whenever takeover must occur, the non-productive system stops first and then takeover occurs. The PREFER_TAKEOVER parameter value is FALSE for Cost Optimized configuration mode. If the PowerHA monitoring script detects failure in SAP HANA database, script tries to restart SAP HANA on the same node if the PREFER_TAKEOVER parameter value is FALSE. You must specify the following additional details for the Cost Optimized configuration mode.
  • Non-productive SAP HANA SID and instance: PowerHA SystemMirror creates the non-production resource group with a fixed node that is secondary node and manages the non-production SAP HANA database by using the new resource group.
  • Global allocation limit: PowerHA SystemMirror uses the global allocation limit value to specify the maximum amount of memory that is used by production SAP HANA memory manager. PowerHA SystemMirror also turns off the table preload of the production SAP HANA database on the secondary node.
  • srHook script password and port number: PowerHA SystemMirror configures the srHook script on the secondary node to cancel the memory limit of the production SAP HANA database and enables table preload when the standby node takes over and becomes the primary node of production SAP HANA database.
    To configure the srHook script, PowerHA SystemMirror updates the following details in the hook script:
    • <SYSTEM password>: The SAP HANA system database password that was defined by user during SAP HANA installation.
    • <Port number>: The port number at which SAP HANA system database listens. For example, 3NN13 or 3NN15, where NN is the instance number of the SAP HANA system database. You must replace NN with the production SAP HANA system database instance number. 30013 is the port number for scenarios with multiple tenants, and 30015 is the port number for scenarios with no tenants.
end of change